JP3395591B2 - Electrode pulse arc welding machine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a welding electrode type pulse arc welding machine for automatically feeding and welding a welding wire (hereinafter referred to as a wire), which is a melting electrode, using a shield gas containing carbon dioxide as a main component. It is a thing.

[0002]

2. Description of the Related Art In recent years, in a welding machine using a shielding gas containing carbon dioxide as a main component, it is required to reduce the amount of spatter generated in welding in order to shorten the post-treatment process for removing deposits such as spatter. ing.

As a method of controlling the output of a welding electrode type pulse arc welding machine using a shielding gas containing carbon dioxide as a main component, the droplets are separated by a pinch force at the beginning of the peak period, and then the wire tip is melted. The droplet is shaped during the base period after it is formed (Japanese Patent Publication No.
31630 gazette). However, in such an output control method, since the droplets are separated during the peak period, the separated droplets may scatter due to the strong arc force of the peak current, resulting in spattering. To prevent this, the phenomenon in which a spike occurs in the welding current waveform each time the droplet breaks off during the peak period is used as the starting point when the timing at which the droplet breaks off is detected, and the droplet melts completely. A method of weakening the influence of the arc force by lowering the welding output until the transition to the pond (Japanese Patent Laid-Open No. 8-318375).
(See Japanese Patent Publication).

However, if the welding output is controlled to be decreased after the droplet detachment is detected, a destabilizing factor of welding occurs every time the droplet detaches, and the droplet detachment is detected in order to stabilize the welding. Then, there was a method of compensating the welding output by extending the peak period in which the welding output was lowered.

[0005]

This method of compensating for welding output stabilizes the welding by changing the peak period in accordance with the fed back welding voltage and in addition performing constant voltage control for a part of the peak period. Can be achieved. However, in such a method, since the peak period in which the droplet detachment is detected is extended, if the pulse period is constant, the base period immediately after the extended peak period becomes short.
In this shortened base period, the droplet formed on the wire end in the peak period immediately before that is incompletely shaped and cannot be separated in the next peak period and grows large. Excessively grown droplets are likely to be sputtered due to the pinch force of the peak current. Further, although the electrode welding with a shield gas containing carbon dioxide as a main component is usually performed in a drop transition state, a short circuit may easily occur depending on welding conditions. In such a state, in the next peak period when the short circuit is accompanied by droplet transfer, it becomes necessary to form a droplet having a detachable size at the tip of the wire. In addition, it is necessary to distinguish between a short circuit without droplet transfer and a short circuit with droplet transfer. The present invention aims to solve the above-mentioned conventional problems.

[0006]

In order to achieve this object, the present invention detects the droplet detachment timing when a shield gas containing carbon dioxide as a main component is used, and then the droplet is completely removed. It is provided with an output control means for controlling the current to be reduced until it is transferred to the molten pool, and immediately thereafter, outputting a pulse waveform starting from the peak period again.

Further, the output control means compares a voltage detector which detects a welding output voltage value and outputs it as a detected voltage value with a detected voltage value from the voltage detector and a reference voltage value from the voltage setting device. Of the detachment detector that outputs a droplet detachment detection signal when the detected voltage value becomes larger than the reference voltage value, and the detected voltage value from the voltage detector and the set value of the reference value setter. From the comparison, a short circuit detector that determines whether the state between the welding wire that is the melting electrode and the welding base material that is the workpiece is a short circuit state or an arc state, and receiving the output of the short circuit detector , A time setter that sets the voltage rise time when transitioning from a short circuit to an arc, and does not accept a droplet detachment detection signal from the detachment detector within the set time of the time setter, and sets the time setter. After the time, the droplet detachment detection signal An output corrector that outputs a fixed output correction signal, a short-circuit time counter that receives the output of the short-circuit detector and counts the total short-circuit time of a short circuit that has occurred within a predetermined time, and the short-circuit time counter Time set by the pulse time setting device until it receives the output correction signal from the output compensator and a pulse time setting device that sets the time for performing the peak current output and the base current output, respectively. Output the pulse waveform signal consisting of the output time and the base current output time, the peak current value set by the peak current setting device and the base current value set by the base current setting device, and output from the output compensator. During the correction time set by the correction time setting device after receiving the correction signal, use the correction level setting device lower than the peak current value set by the peak current setting device. The corrected peak current value is output, and after the correction time has elapsed, the peak current output time set by the pulse time setting device and the base current output time and the peak current value set by the peak current setting device and the base current setting device are set again. And a pulse waveform generator that outputs a pulse waveform signal including a set signal with a set base current value so as to start from a peak current value.

[0008]

With the above structure, the output current is decreased from the peak current value during the period from the start of droplet separation to the complete transfer of the droplet to the molten pool, and after the droplet transfer, a pulse is restarted from the peak period. A waveform can be output, and the arc force can be weakened during droplet transfer, so droplets can be stably transferred to the molten pool, and it is possible to reduce the occurrence of spatter that causes droplets to fly outside the molten pool. By setting the peak current immediately after the transition, it is possible to prevent arc instability such as arc breakage and to perform low spatter and high quality welding.

An embodiment of the present invention will be described below with reference to FIG. In FIG. 1, 1 is an output control element, 2 is a main transformer, 3 is a rectifier, 4 is a reactor, 5 is a wire, 6 is a wire feeding motor, 7 is a welding torch, 8 is a current-carrying electrode, and 9 is a welding base material. 10 is a current detector, 11 is an output drive controller, 12 is a current detector, 13 is a voltage detector,
Reference numeral 14 is a voltage setting device, 15 is a departure detector composed of a comparator and an operational amplifier, 16 is a reference value setting device, and 17 is a reference value setting device.
Is a short-circuit detector composed of a comparator or operational amplifier, 18 is a time setting device, 19 is an output compensator, 20 is a pulse time setting device, 21 is a peak current setting device, 22 is a base current setting device, and 23 is a correction time setting device. , 24 is a correction level setting device, 25 is a pulse waveform generator, and 26 is a short circuit time counter. The operation of the melting electrode type pulse arc welding machine configured as described above will be described. The detection voltage value of the voltage detector 13 for detecting the welding output voltage and the reference voltage value of the voltage setting device 14 are input to the detachment detector 15, and the detachment detector 1
5 outputs a droplet detachment detection signal when the detected voltage value becomes larger than the reference voltage value. By inputting and comparing the set value of the reference value setter 16 and the detected voltage value from the voltage detector 13, the state between the wire 5 which is the melting electrode and the welding base material 9 which is the work piece is short-circuited. The short-circuit detector 17, which determines whether there is an arc state or an arc state, outputs the determination result of the short-circuit arc to the time setter 18 and the short-circuit time counter 26. Further, the time setter 18 sets the voltage rise time when the short-circuit is switched to the arc and outputs it to the output compensator 19.
The output compensator 19 includes a departure detector 15 and a time setter 18.
Signal is received as an input, the droplet detachment detection signal from the detachment detector 15 is not accepted within the set time of the time setter 18, and the droplet detachment detection signal is received after the set time of the time setter 18 and output correction Output a signal. Further, the short-circuit time counter 26 receives the signal from the short-circuit detector 17, counts the total short-circuit time of a short circuit that has occurred within a predetermined time, and outputs it to the pulse time setter 20. The output correction signal of the output corrector 19, the set value of the peak current output time and the base current output time set by the pulse time setting device 20, the peak current value set by the peak current setting device 21, and the base current setting device 22 The set base current value, the correction time set by the correction time setting device 23, and the correction peak current value set by the correction level setting device 24 are input to the pulse waveform generator 25. In the output drive controller 11, the signal output from the pulse waveform generator 25 is used as a reference waveform.
The output control element 1 is driven so that the output current is compared with the output current value detected by the current detector 12, and the output current matches the reference waveform.

The operation of the pulse waveform generator 25 will be described here. As a basic output during welding, the pulse waveform generator 25 selects the peak current value set by the peak current setting device 21 within the peak current output time set by the pulse time setting device 20, and within the base current output time The base current value set by the base current setter 22 is selected, and a pulse waveform in which the peak and the base are repeated at a constant cycle is output to the output drive controller 11. Here, the peak current output time is 4 to 15 ms, the base current output time is 2 to 10 ms,
Peak current value is 380-520A, base current value is 60
~ 90A. For this basic operation, the output compensator 1
When the output correction signal is input from 9, the following operation is performed. That is, the output current is corrected while the input of the output correction signal is used as the starting point of time counting and the correction time given by the correction time setting device 23 for setting the time required for the droplets to move to the molten pool elapses. The corrected peak current value set by the level setter 24 is selected as the output command value and output to the output drive controller 11. Corrected peak current value is 200-30
It is a value of 0A. After the correction time has elapsed, the peak current value set by the peak current setting device 21 is again selected as the output command value, and the peak current output time is output by the pulse time setting device 20. Continuously pulse time setting device 2
Within the base current output time set at 0, the base current value set by the base current setter 22 is selected, and thereafter, a pulse waveform in which the peak and the base are repeated at a constant cycle is output again to the output drive controller 11.

Next, the departure detector 15 and the output compensator 19
The operation of will be described. The detachment detector 15 compares the detected voltage value from the voltage detector 13 and the reference voltage value from the voltage setting device 14 and outputs a droplet detachment detection signal when the detected voltage value becomes larger than the reference voltage value. Output. However, in pulse arc welding using a shield gas containing carbon dioxide as a main component, droplet transfer is usually performed in a drop transfer state, but in some cases a short circuit may occur, and a short circuit is followed by an arc. The voltage suddenly rises. Therefore, if the voltage is detected and it is immediately determined that the droplet has separated, there is a possibility that an erroneous detection may occur. In order to prevent this erroneous detection, the output compensator 19 does not accept the output signal from the departure detector 15 for a certain period of time after the short circuit is opened. The fixed time from the opening of the short circuit is set by the time setter 18 which receives the output signal from the short circuit detector 17 which detects the short circuit according to the detected voltage value from the voltage detector 13 and the set value from the reference value setter 16. It Also, the output compensator 19
Does not receive the droplet detachment detection signal from the detachment detector 15 within a fixed time after the short circuit opening set by the time setter 18. Usually this time is 0.5-2 ms.

As described above, in the welding electrode type pulse arc welding machine according to the present embodiment, the peak current and the base current are alternately output, and the droplets at the tip of the wire are released during the peak period for welding. An output control means capable of lowering the output current from the peak current value during the period from the start of droplet detachment to the complete transfer of the droplet to the molten pool, and outputting a pulse waveform starting from the peak period again after the transfer of the droplet. By providing I, droplets can be regularly and reliably transferred to the molten pool, and the generation of spatter can be reduced.

[0013]

As is apparent from the above description, according to the present invention, the peak current and the base current are alternately output, and the main component is carbon dioxide gas for welding by separating the droplets from the tip of the wire during the peak period. It is a droplet type pulse arc welding machine that uses a shield gas that reduces the output current below the peak current value during the period from the start of droplet detachment to the complete transfer of droplets to the molten pool. By providing the output control means that can output the pulse waveform starting from the peak period again, the arc force can be weakened during the droplet transfer, so that the droplets can regularly and reliably transfer to the molten pool, It is possible to reduce the generation of spatters scattered outside the molten pool and to prevent arc breakage immediately after the droplets are separated, so that stable and high quality welding can be realized.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a welding electrode type pulse arc welding machine according to an embodiment of the present invention.

[Explanation of symbols]

13 Voltage detector 14 Voltage setting device 15 Detachment detector 16 Reference value setter 17 Short circuit detector 18 hour setter 19 Output corrector 20 pulse time setting device 21 Peak current setting device 22 Base current setting device 23 Correction time setting device 24 Correction level setting device 25 pulse waveform generator 26 Short-circuit time counter I output control means

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B23K 9/09

Claims (2)

(57) [Claims] 1. A melting method using a shield gas containing carbon dioxide as a main component, which alternately outputs peak current and base current, and separates droplets at the tip of the welding wire, which is a melting electrode, during the peak period to perform welding. It is a polar type pulse arc welding machine,
Is the state between the welding wire and the work piece short-circuited?
A short-circuit detector that determines whether it is in an arc state, and the short-circuit
Predetermined time after inputting the signal from the detector
Short circuit counter for counting the total short circuit time of short circuits
And receiving the output of the short-circuit time counter,
Force and base current output time.
A loose time setting device and a detachment detector that detects detachment of droplets,
Period from droplet detachment start until droplet is completely shifts to the molten pool reduces the peak current value output current, pulse for outputting a pulse wave that starts again from the peak period after droplet transfer
A welding electrode type pulse arc welding machine having an output control means provided with a waveform generator . 2. The output control means compares a voltage detector that detects a welding output voltage value and outputs it as a detection voltage value with a detection voltage value from the voltage detector and a reference voltage value from a voltage setting device. A detachment detector that outputs a droplet detachment detection signal when the detected voltage value becomes larger than the reference voltage value;
From the comparison between the detected voltage value from the voltage detector and the set value of the reference value setting device, the state between the welding wire which is the melting electrode and the welding base material which is the workpiece is in the short-circuit state or in the arc state. There is a short-circuit detector that determines whether there is, a time setter that receives the output of the short-circuit detector and sets the voltage rise time when transitioning from a short circuit to an arc, and the disconnection within the set time of the time setter. Not accepting the droplet detachment detection signal from the detector, after the set time of the time setter, receiving the droplet detachment detection signal and outputting the output correction signal, and receiving the output of the short-circuit detector, A short-circuit time counter that counts the total short-circuit time of a short circuit that has occurred within a predetermined time, and a pulse time that receives the output of the short-circuit time counter and sets the time for performing peak current output and base current output, respectively. Controller and the peak current output time and base current output time set by the pulse time setting device and the peak current value and base current setting device set by the peak current setting device until the output correction signal from the output correction device is received. Output a pulse waveform signal consisting of a setting signal with the base current value set in, and during the correction time set by the correction time setting device after receiving the output correction signal from the output correction device, the peak current setting Outputs the corrected peak current value set by the correction level setting device that is lower than the peak current value set by the setting device.After the correction time elapses, the peak current output time, base current output time and peak current set by the pulse time setting device are output again. Start the pulse waveform signal consisting of the setting signal of the peak current value set by the potentiometer and the base current value set by the base current potentiometer from the peak current value. Consumable electrode type pulsed arc welder of claim 1, further comprising a pulse waveform generator for outputting to so that.