JP2006116561A - Arc welding control method and arc welding equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an arc start control method where the amount of spatters to be generated in a meanwhile from the generation of an arc to its stabilization, and to provide arc welding equipment. <P>SOLUTION: In the arc welding control method where welding current is fed between a base material and an electrode while it is controlled, and an arc is generated, so as to perform welding, at the start of the arc, one or more pulse wave-shaped electric currents are fed by a pulse control 37, a molten pool to be formed at first on the base material is formed by the departure transit of droplets, and, after the feed of the pulse wave-shaped electric currents, it is changed from the pulse control 37 to a short-circuit control 36. Further, the tip of an arm in an arc welding robot is mounted with the electrode, and at tie time of lift up start where the tip of the arm is lifted up at the start of the arc, the above control is performed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an arc welding control method and arc at the time of arc start of a consumable electrode type arc welding apparatus that performs welding output control by generating an arc between a welding wire that is a consumable electrode and a base material that is a workpiece. The present invention relates to a welding apparatus.

  In recent years, in the welding industry, there has been an increasing demand for high-quality welding in order to improve productivity. In particular, there is a reduction in spatter during arc start. At the time of arc start, since it takes time until the molten pool is formed, it takes time until the arc is stabilized, and the occurrence of spatter increases and often adheres to the workpiece. And the post-process for removing adhesion spatter is needed, and welding productivity will fall.

  In the conventional arc start control, an arc start current having a large current increase rate is supplied when the wire comes into contact with the base material to improve the arc generation performance (see, for example, Patent Document 1).

  FIG. 3 shows the configuration of a conventional arc welder that performs arc start control, wherein 1 is an input terminal of the arc welder, 2a and 2b are open / close switch elements of the main power source of the arc welder, and the switch element 2b is The switching element 2a and the switching operation are reversed. 3 is a transformer, 4 is a secondary rectifier, 5 is a welding output control element, 6 is a regenerative diode, 7 is a reactor (DCL), 8a is a + side output terminal of the arc welder, and 8b is a-side of the arc welder. An output terminal, 9 is a base material to be welded, 10 is a welding wire that is a consumable electrode, and 11 is a contact tip for energization. The welding wire 10 is automatically fed, and welding is performed by repeating contact short-circuiting to the base material of the welding wire 10 and non-contact arc generation. In this arc welder control circuit, reference numeral 12 denotes a shunt, and reference numeral 13 denotes a welding current detector, which outputs a current detection signal that changes the state depending on whether the welding current is flowing or not. 14 is a welding start switch, VTS is a welding start signal, 15 is a main control unit, 16 is a gate control unit, 17 is a thyristor, 18 is a diode, 19 is a first resistor, 20 is a capacitor, and 21 is a second resistor. . The thyristor 17 and the diode 18 are connected to the + side output terminal 8 a, and the gate signal of the thyristor 17 is controlled by the gate controller 16. One end of the first resistor 19 is connected to the cathode of the diode 18, and the other end is connected to the anode of the thyristor 17 and the + terminal of the capacitor 20. The minus terminal of the capacitor 20 is connected to the minus side output terminal of the arc welder, and the second resistor 21 and the switch element 2b are connected in series with the capacitor 20 in parallel.

Next, the operation of the arc welder shown in FIG. 3 will be described. The main power supply of the arc welder is turned on, the contact 2a is closed, and the contact 2b is opened. Then, the welding start switch 14 is turned on, and the welding output control element 5 is turned on by the action of the main control unit 15 together with the start of wire feeding (not shown). As a result, a no-load voltage is output between the output terminals 8a and 8b of the arc welder, and this voltage charges the capacitor 20 via the diode 18 and the first resistor 19, whereby the voltage across the capacitor 20 rises. . At the same time, the gate control unit 16 gives a gate signal for instructing the thyristor 17 to turn ON. Since the wire 10 contacts the base material 9 in this state, the charge charged in the capacitor 20 is as follows: the thyristor 17 → the + side output terminal 8a → the contact tip 11 for energization → the wire 10 → the base material 9 → the −output terminal 8b. The welding current can be increased at the time indicated by 101 in FIG. 4 showing the moment when the wire 10 contacts the base material 9, and the tip of the wire 10 is rapidly heated and melted to generate a welding arc.
JP-A-3-204175

  However, the output control in the conventional arc welder improves the arc generation performance and reduces the spatter at that time, but since the molten pool does not exist in the base material 9 at the first short circuit after the arc generation, the tip of the wire 10 Cannot be smoothly transferred to the base material 9, and most of the droplets are spattered and scattered. FIG. 4 shows the current waveform of the welding current. Since there is no molten pool in the base material 9 at the time of the first short circuit after the occurrence of the arc, the short circuit period 105 becomes longer as shown in FIG. To increase.

  An object of the present invention is to provide an arc start control method and an arc welding apparatus that reduce the amount of spatter generated until an arc is generated and the arc is stabilized.

  In order to solve the above problems, an arc welding control method of the present invention is an arc welding control method for performing welding by generating an arc by supplying a welding current between a base material and an electrode while controlling the welding current, Supplying one or more pulse-wave currents by pulse control at the time of arc start to form a molten pool that is initially formed on the base material by detachment transition, and switching from pulse control to short-circuit control after supplying pulse-wave currents It is.

  The arc welding apparatus according to the present invention includes a welding current detection unit that detects a welding output current, a welding voltage detection unit that detects a welding output voltage, a current parameter for short-circuit control, a voltage parameter, and a current parameter for pulse control. And a setting unit for setting the voltage parameter and timing for switching from pulse control to short-circuit control, the output of the welding current detection unit, the output of the welding voltage detection unit, and the output of the setting unit as inputs, and pulse control immediately after the occurrence of an arc. A pulse control unit to perform; a switching unit that outputs the timing of switching from pulse control to short-circuit control using the output of the setting unit as an input; the output of the welding current detection unit; the output of the welding voltage detection unit; and the output of the setting unit A short-circuit control unit that performs short-circuit control with the input, an output of the pulse control, an output of the switching unit, and an output of the short-circuit control Those with a drive for controlling by switching a short circuit control and pulse control in accordance with the output of the switching unit.

  As described above, sputtering can be reduced by applying one or more pulse currents after the occurrence of an arc and switching to short-circuit control after a predetermined time has elapsed or after a predetermined pulse has been applied.

  Moreover, the arc welding control method of the present invention is performed by combining the above-described control when a lift-up start is performed in which an electrode is mounted on the arm tip of an arc welding robot and the arm tip is pulled up at the time of arc start.

  In the arc welding apparatus of the present invention, the current parameter and voltage parameter of the pulse control unit set by the setting unit and the switching timing of the switching unit are set current value, set voltage value, wire feed amount, shield gas It is set based on at least one of the type, wire material, wire diameter, and welding method.

  As described above, according to the present invention, after the arc occurrence, the molten metal at the tip of the wire is transferred to the base metal by pulse control of the welding current to form a molten pool, and then the short-circuit control is performed to switch to the short-circuit. When the droplet is short-circuited to the molten pool, the droplet smoothly moves to the molten pool, and the occurrence of spatter can be reduced.

(Embodiment 1)
FIG. 1 shows a schematic configuration of an arc welding apparatus in the present embodiment. In FIG. 1, 40 is an input power source, 31 is a primary rectifier for rectifying the output of the input power source 40, 32 is a switching element for controlling the welding output, 3 is a transformer for insulating and converting power, 4 is a transformer 3 A secondary rectifier 7 for rectifying the secondary output, 7 is a reactor (DCL).

  Reference numeral 35 denotes, for example, the magnitude of the pulse current or the pulse time based on setting conditions such as a setting current, a setting voltage, a wire feed amount, a shield gas type, a wire type, a wire diameter, and a welding method inputted by an input means (not shown). Is a setting unit that sets and outputs various parameters such as. The setting unit 35 includes a storage unit (not shown) for storing the table and formula for obtaining the parameters, and a calculation unit (not shown) for performing calculations and the like. Is.

  39 is a welding voltage detector for detecting the welding voltage, 33 is a welding current detector for detecting a welding current, and 37 is an output of the welding current detector 33, an output of the welding voltage detector 39, and an output of the setting unit 35. This is a pulse control unit that outputs a command for performing pulse control of welding current as an input. As will be described later, after an arc start current for generating an arc flows, a pulsed current flows for a predetermined time. Control is performed. A short-circuit control unit 36 outputs a command for performing a short-circuit control of the welding current using the output of the welding current detection unit 33, the output of the welding voltage detection unit 39, and the output of the setting unit 35 as inputs. Note that, as an example, the pulse control unit 37 and the short-circuit control unit 36 compare a current value as a parameter input from the setting unit 35 with a current value input from the welding current detection unit 33 to detect a welding current. It has a function of performing correction so that the current value detected by the unit 33 becomes a current value as a parameter.

  Reference numeral 38 denotes a switching unit that takes the output of the setting unit 35 as an input and outputs the timing of switching the current waveform control from pulse control to short-circuit control to the drive unit 34 described later. The switching unit 38 has a time measuring function, and can measure the time from when the output of the setting unit 35 is input until a predetermined time elapses.

  Reference numeral 34 denotes a drive unit that receives the output of the short-circuit control unit 36, the output of the pulse control unit 37, and the output of the switching unit 38, and controls the switching between the pulse control and the short-circuit control in accordance with the output of the switching unit 38. It has a function of switching whether to output the output of the short-circuit control unit 36 to the switching element 32 or to output the output of the pulse control unit 37 to the switching element 32 according to the output of the unit 38.

  The arc start control method in the arc welding apparatus configured as described above will be described.

  FIG. 2 shows an example of a welding current waveform at the time of consumable electrode arc welding. In FIG. 2, an arc generation current for generating an arc flows at time 101, an arc is generated, and then a pulsed current flows twice by pulse control, and then a short circuit current flows by short circuit control. An example of a welding current waveform is shown.

  At the time of arc generation time 101, the drive unit 34 outputs the output of the pulse control unit 37 to the switching element 32 based on the input from the switching unit 38. Further, information related to a predetermined elapsed time from the occurrence of an arc, which is a condition for switching from the pulse control set in the setting unit 35 to the short-circuit control, is output from the setting unit 35 to the switching unit 38 and stored in the switching unit 38. . In the present embodiment, the time from time 101 to time 102 shown in FIG. 2 is a predetermined elapsed time.

  Information on the occurrence of arc is output from the setting unit 35 to the switching unit 38, and the switching unit 38 starts measuring time. Pulse control of the welding current is performed based on the output of the pulse control unit 37 from the arc generation time point 101 to the switching time point 102 until the switching time point 102 is reached, and the droplet at the tip of the welding wire (not shown) is removed. Move to a base material (not shown). Then, when a predetermined time elapses from the arc generation time point 101 and becomes the switching time point 102, the switching unit 38 gives a switching instruction to the driving unit 34, whereby the output of the short-circuit control unit 36 is sent to the switching element 32. Therefore, the welding current control is switched from the pulse control to the short-circuit control. After the switching time point 102, the short-circuit control unit 36 performs short-circuit control.

  In the above description, an example in which the control of the welding current is switched from the pulse control to the short-circuit control when the predetermined time has elapsed from the arc generation time 101 has been shown. You may make it switch from pulse control to short circuit control by making the time point when the preset number of pulses was applied instead of progress of time into the switching time point 102. FIG. In this case, the switching unit 38 has a function of counting the number of pulses. By counting the number of pulses input from the setting unit 35, an instruction to switch the current waveform control from pulse control to short-circuit control is driven. This is output to the unit 34.

  As described above, the arc start control method and the arc welding apparatus according to the present embodiment provide the molten pool first formed on the base material by supplying one or more pulse wave currents by pulse control after the arc start current flows. Is formed by detachment transition, and after the pulse wave current is supplied, the control is switched from the pulse control to the short-circuit control.

  According to the arc start control method and the arc welding apparatus of the present embodiment, since the molten pool can be formed by the separation transition by supplying one or more pulse wave currents by the pulse control from the time of the arc generation, the short circuit transition A molten pool can be formed without causing a short circuit, so that even when switching from pulse control to short circuit control, the droplet at the tip of the wire smoothly transitions to short circuit, so that spatter is generated from when the arc occurs until the arc stabilizes. In addition, spatter adhesion can be reduced.

  In the present embodiment, an example in which a pulsed current flows twice after the arc start current at the time point 101 flows is shown, but the present invention is not limited to two times and may be one or more times. That's fine.

  In addition, the arc start control described above is performed when a lift-up start is performed by combining the arc welder and the arc welding robot, mounting a welding wire as an electrode on the arm tip of the arc welding robot, and pulling up the arm tip at the time of arc start. May be performed. By lifting up at the arc generation time point 101, the welding wire is prevented from melting and becoming spatter in a short-circuit state to reduce spatter at the arc generation time point 101, and by lifting up, the wire tip and the base metal Can be obtained instantaneously, that is, a distance wider than the droplet size at the time of pulse control can be obtained instantaneously. Thus, the generation and adhesion of spatter can be further reduced.

  Here, as a timing for lifting up, it is possible to flow a small current of 100 A or less before the arc generation time 101 to ensure the contact between the welding wire and the base material, and lift up at that time.

  The set current value and the set voltage value as parameters set by the setting unit 35 and output to the short-circuit control unit 36 and the pulse control unit 37, and the switching timing set by the setting unit 35 and output to the switching unit 38 are as follows: Set by the setting unit 35 based on at least one of the set current value, set voltage value, wire feed amount, shield gas type, wire material, wire diameter, and welding method input to the setting unit 35. Is. By doing in this way, a parameter can be set up for every various setting conditions, and the adaptation to various welding spreads.

  Moreover, the above-described control of the welding current can be applied to MAG (metal active gas) welding and MIG (metal inert gas) welding which cause separation transition.

  The arc start control method and arc welding apparatus of the present invention are useful in the field of welding and the like because they can reduce spatter generation and spatter adhesion at the time of arc start and improve the productivity of welding work.

The figure which shows the whole structure in Embodiment 1 of the arc welding apparatus of this invention. The figure which shows the welding current waveform in Embodiment 1 of the arc welding apparatus of this invention. The figure which shows the whole structure of the arc welding apparatus of a prior art example The figure which shows the welding current waveform in the arc welding apparatus of a prior art example

Explanation of symbols

DESCRIPTION OF SYMBOLS 3 Transformer 4 Secondary rectification part 7 Reactor 31 Primary rectification part 32 Switching element 33 Welding current detection part 34 Drive part 35 Setting part 36 Short-circuit control part 37 Pulse control part 38 Switching part 39 Welding voltage detection part 40 Input power supply 101 Arc generation Time point 102 Switching time point 103 Pulse control period 104 Short-circuit control period 105 Short-circuit period

Claims (6)

An arc welding control method for performing welding by generating an arc by controlling a welding current between a base material and an electrode, and supplying one or more pulse wave currents by pulse control at the start of the arc. An arc welding control method for switching from pulse control to short-circuit control after forming a molten pool formed first in the base material by detachment transfer and supplying a pulse-shaped current. 2. The arc welding control method according to claim 1, wherein an electrode is mounted on an arm tip of an arc welding robot, and the arc welding control method is performed when a lift-up start is performed to pull up the arm tip when the arc starts. The arc welding control method according to claim 1 or 2, which is used for MAG welding or MIG welding. Welding current detection unit for detecting welding output current, welding voltage detection unit for detecting welding output voltage, current parameter and voltage parameter for short circuit control, current parameter for pulse control, voltage parameter and pulse control to short circuit control A setting unit for setting a switching timing, a pulse control unit for performing pulse control immediately after the occurrence of an arc using the output of the welding current detection unit, the output of the welding voltage detection unit, and the output of the setting unit as inputs, and the setting unit A switching unit that outputs the timing of switching from pulse control to short-circuit control using the output as input, and a short-circuit control unit that performs short-circuit control using the output of the welding current detection unit, the output of the welding voltage detection unit, and the output of the setting unit as inputs. The output of the pulse control, the output of the switching unit, and the output of the short circuit control are input, and the output is output according to the output of the switching unit. A drive unit for controlling switching a scan control and short circuit control, arc welding device to switch to short-circuit control is applied to one or more pulse after arc generation after or after a predetermined pulse application a predetermined time elapses. 5. An arc welding apparatus according to claim 4, wherein an electrode is mounted on the tip of the arm of the arc welding robot, and the lift-up start is performed to raise the tip of the arm when starting the arc. The current parameter and voltage parameter of the pulse control unit set by the setting unit and the switching timing of the switching unit are set current value, set voltage value, wire feed amount, shield gas type, wire material, wire diameter, welding The arc welding apparatus according to claim 4, wherein the arc welding apparatus is set based on at least one element of the method.

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