Abstract: A welding device includes a power supply circuit for applying a voltage across a torch and a base metal, and a power supply control device. The power supply control device controls the power supply circuit such that a high level current is output during a first arc period Ta1 that is the initial period of an arc period, and an arc current corresponding to a regulated welding voltage is output during a second arc period Ta2 that is the latter period of the arc period. The power supply control device controls the power supply circuit such that a high level current is generated having a waveform increasing and decreasing at a constant frequency and constant amplitude superimposed on the high level current. By superimposing the waveform, the elevation of a droplet caused by an repelled force by the arc can be prevented, allowing a droplet to be formed in stabilization.

Abstract: A squeezing detection control method is provided for consumable electrode arc welding. The method includes a step of detecting a droplet squeezing phenomenon by checking that a change in a voltage or resistance between the consumable electrode and base material reaches a squeezing detection reference value, and a step of executing output control for rapidly decreasing a welding current passing through a short-circuited load when the squeezing phenomenon is detected, so that arc re-striking occurs in a state of low current. The squeezing detection reference value is set to a first value during the electrode positive polarity, and set to a second value during the electrode negative polarity. The second value is different from the absolute value of the first value, and each of the first and second values is set such that the resultant welding state is satisfactory.

Abstract: A welding current controlling method is provided for an arc welding process using a consumable electrode and including an alternate repetition of a short-circuiting state and an arc generating state occurring between the consumable electrode and a base material. In the method, a neck detection is performed for the molten electrode in the short-circuiting period of time to determine if a new arc is established between the consumable electrode and the base material. Upon detection of the neck, the welding current is sharply decreased. After the new arc is established, the welding current is increased from a low level to a high level with a predetermined inclination selected for reducing vibration to the molten pool.

Abstract: A method of performing polarity switching short circuiting arc welding is provided. In the arc welding, a welding wire is fed at a constant feeding rate, a short circuiting state and a arcing state appear repeatedly between the welding wire and a base metal, and the output polarity of a welding power source is switched in accordance with a polarity switching signal for performing electrode positive welding and electrode negative welding. In accordance with the method, the welding current is reduced during a predetermined short circuit initial period, when a first arc is formed after the polarity switching signal changes. Then, the output polarity of the welding power source is changed when the short circuit initial period has lapsed. Further, the welding current is increased for terminating the arc forming between the welding wire and the base metal.

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: The control system includes a welding robot which moves a welding torch along a work for welding the work. A robot controller controls driving of the welding robot. A laser sensor head detects a shape change in the work during welding by the welding torch, and a personal computer obtains instruction information for the welding robot in accordance with the shape change, based on a result of detection by the laser sensor head. The robot controller moves the welding torch by controlling the driving of the working robot, based on the instruction information obtained by the personal computer.

Abstract: An arc welding power source supplies a start current, a welding current and a crater current as an output current in accordance with an activating signal supplied from outside. The power source includes a start period setting unit, a crater period setting unit, and a current control unit that controls the output current. The current control unit causes the power source to supply the start current and the welding current consecutively while the activating signal is in an on-state, where the start current is supplied for the start period, and the welding current is supplied for the period following the start period. The current control unit also causes the power source to supply the crater current after the activating signal is turned off, where the crater current is supplied for the crater period.

Abstract: A feed control method is provided for consumable electrode AC arc welding, in which the welding wire is fed at a predetermined wire feed rate, and a welding voltage applied to an arc is switched in alternation between electrode positive polarity and electrode negative polarity. In the method, a welding current setting signal is generated, and the wire feed rate is set to a first feed rate during a period of the electrode positive polarity, based on both the wire welding characteristics for the electrode positive polarity and the welding current setting signal. Further, the wire feed rate is set to a second feed rate during a period of the electrode negative polarity, based on both the wire welding characteristics for the electrode negative polarity and the welding current setting signal.

Abstract: A squeezing detection control method is provided for consumable electrode arc welding. The method includes a step of detecting a droplet squeezing phenomenon by checking that a change in a voltage or resistance between the consumable electrode and base material reaches a squeezing detection reference value, and a step of executing output control for rapidly decreasing a welding current passing through a short-circuited load when the squeezing phenomenon is detected, so that arc re-striking occurs in a state of low current. The squeezing detection reference value is set to a first value during the electrode positive polarity, and set to a second value during the electrode negative polarity. The second value is different from the absolute value of the first value, and each of the first and the second values is set such that the resultant welding state is satisfactory. (FIG .

Abstract: A squeezing detection control method is provided for consumable electrode arc welding in which a cycle of arc generation and short-circuiting is repeated between a consumable electrode and a base metal. First, squeezed droplet is detected as a premonitory sign of arc recurrence at the end of the short-circuiting. This detection is based on a fact that a squeeze detection reference value is attained by a differential value of the voltage or resistance between the consumable electrode and the base metal. Then, a welding current supplied to a short-circuit load is rapidly decreased upon detection of the squeezed droplet. Upon recurrence of the arc, the welding current is increased. This arc recurrence is detected by a fact that the differential value attains an arc recurrence reference value which is greater than the squeeze detection reference value.

Abstract: The control system includes a welding robot (10) which moves a welding torch (16) along a work (W) for welding the work (W), a robot controller (40) for controlling driving of the welding robot (10), a laser sensor head (17) for detecting a shape change in the work (W) during welding by the welding torch (16), and a personal computer (30) for obtaining instruction information for the welding robot (10) in accordance with the shape change, based on a result of detection by the laser sensor head (17). The robot controller (40) moves the welding torch (16) by controlling the driving of the working robot, based on the instruction information obtained by the personal computer (30).

Abstract: In the output control method for a consumable electrode arc welding power source, entire application range of an welding current is segmentalized into a plurality of current zones, a norm welding voltage value is set for each of the current zones, a welding current and a welding voltage are detected at each of minute cycles, the current zone which corresponds to a detected value of the welding current is selected, a fluctuation range is calculated with the norm welding voltage value of the selected current zone as a center value, a welding voltage limit value is calculated while the welding voltage detected value is limited to within the fluctuation range, and the output of the welding power source is controlled based on this welding voltage limit 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 welding current controlling method is provided for an arc welding process using a consumable electrode and including an alternate repetition of a short-circuiting state and an arc generating state occurring between the consumable electrode and a base material. In the method, a neck detection is performed for the molten electrode in the short-circuiting period of time to determine if a new arc is established between the consumable electrode and the base material. Upon detection of the neck, the welding current is sharply decreased. After the new arc is established, the welding current is increased from a low level to a high level with a predetermined inclination selected for reducing vibration to the molten pool.

Abstract: A method of performing polarity switching short circuiting arc welding is provided. In the arc welding, a welding wire is fed at a constant feeding rate, a short circuiting state and a arcing state appear repeatedly between the welding wire and a base metal, and the output polarity of a welding power source is switched in accordance with a polarity switching signal for performing electrode positive welding and electrode negative welding. In accordance with the method, the welding current is reduced during a predetermined short circuit initial period, when a first arc is formed after the polarity switching signal changes. Then, the output polarity of the welding power source is changed when the short circuit initial period has lapsed. Further, the welding current is increased for terminating the arc forming between the welding wire and the base metal.