JPH0822459B2 - Consumable electrode type pulse welding power supply - Google Patents

Description

TECHNICAL FIELD The present invention relates to a consumable electrode for performing welding by splitting a welding current into a pulse portion and a base portion and outputting the welding current interchangeably to separate the molten portion at the tip of the welding wire in a spray form. The present invention relates to a power source for pulse welding.

2. Description of the Related Art The pulse current rising slope and the pulse current falling slope of the conventional consumable electrode type pulse welding power source are determined by the reactor in the welding power source connected in series with the welding arc. Therefore, in order to change these gradients, the number of turns of the reactor was changed to slow down the pulse current gradient by using an extension cable and improve the arc characteristics. Also,
Welding output control elements are controlled in detail to change the rising and falling gradients of the pulse current to prevent arc blow phenomenon and improve the arc characteristics of conventional pulse welding power supplies. A separate adjuster, which is irrelevant to the setting of the fine adjuster to be finely adjusted, was used to manually set according to the situation.

DISCLOSURE OF THE INVENTION Problems to be solved by the invention In pulse welding, since the molten mass at the tip of the wire is dissociated in a spray form and transferred without causing the welding wire to come into contact with the object to be welded, spatter generation is extremely small. However, as the welding speed is increased, the non-contact state causes insufficient welding of the wire in spite of the spread of the arc, and as a result, welding defects such as undercut are likely to occur. In order to prevent this undercut, in order to suppress the spread of the welding arc, the worker lowers the welding voltage and shortens the arc length to perform welding.However, as the arc length becomes shorter, the welding wire becomes welded. The frequency of contact short-circuiting with the object increases, which causes remarkable spattering and impairs the low sputtering performance, which is a characteristic of pulse welding. Analysis of the state of spatter generation revealed that the probability of contact short-circuiting at the trailing edge of the pulse current immediately after the end of pulse application and transfer of the droplet gas spray was extremely high. For example, for mild steel 1.2 mm diameter wire, about 450
There is a high probability of contact short-circuiting in the current sloping portion that falls from the pulse peak current of A to the base current of about 50 A, and spatter generation becomes significant due to this large current value. If this contact short circuit is generated in the base part, spatter generation is not so remarkable at a base current of about 50A. Therefore, when high-speed welding is performed with the welding voltage set to a low value, rapid pulse application is used to ensure and speed up spray transfer. It is necessary to switch to a base part that rarely occurs.

However, it is preferable that the rise and fall of the pulse current are not steep in the normal speed welding that secures the arc length and is not high speed welding. The reason for this is that as the current value changes abruptly, the vibration of the molten pool due to the arc force becomes severe and the weld bead becomes unsatisfactory, and the steep pulse current causes a high metallic arc noise and impairs workability. Is.

As described above, the rise of the pulse current according to the welding speed,
Good welding results cannot be obtained in all regions unless the fall is changed, whereas in conventional welding machines, the rise of pulse current is uniquely caused by the reactor connected in series with the welding arc,
Even in the conventional machine that can set the trailing edge and change the pulse current trailing gradient by electronic superposition, the adjustment is performed by the welding operator depending on the situation to prevent the arc blow phenomenon from occurring regardless of the welding speed. Had to make manual adjustments.

Means for Solving the Problems In order to solve the above problems, the present invention uses at least one of a welding voltage and an arc length as an input, and provides a current setting value of a pulse current part and a current setting value of a base current part. The current setting value signal that sets the value alternately, the pulse rising slope setting signal that sets the rising speed of the pulse current when moving from the base part to the pulse part, and the pulse current of the pulse current when moving from the pulse part to the base part. An arithmetic circuit unit that outputs a pulse falling slope setting signal that sets a falling speed, the current setting value signal, the pulse rising slope setting signal, and the pulse falling slope setting signal as input, and the current setting value A current command that becomes a current setting value from the base section to the pulse section with a temporal gradient determined by the pulse rising gradient setting signal when the signal transitions from the base section to the pulse section A value signal, and a current that becomes a current set value from the pulse part to the base part with a temporal gradient determined by the pulse falling slope setting signal when the current set value signal transitions from the pulse part to the base part A pulse gradient control circuit unit that outputs a command value signal, the current command value signal and the current detection value signal from the welding current value detection circuit unit are input, and the current command value and the current detection value are compared and the welding current is compared. A comparison control circuit unit for controlling the value to match the current command value and outputting a control signal to the welding output control element, and when the welding voltage is low or the arc length is short, the pulse rising slope When the welding voltage is high or the arc is set, the temporal gradient determined by the setting signal and the temporal gradient determined by the pulse falling gradient setting signal are set to a steep large value. Is one that when long was slow small becomes a value temporal gradient is determined by the temporal gradient and the pulse fall gradient setting signal is determined by the pulse rise gradient setting signal.

Action Due to the above configuration, when the welding voltage is low or the arc length is short, it is expected that the welding is a wire-welded short circuit including high-speed welding. As a result, the pulse rising slope and the pulse falling slope are set to steep and large values, and as a result, even if a large number of wire contact short circuits occur, it is more likely to cause them to occur during the base period when the current is low, and spatter generation is reduced. be able to. On the contrary, when the welding voltage is high or the arc length is long, it is expected that the welding is one in which the wire contact short-circuit is small, so that the pulse rising slope and the pulse falling slope are set to slow and small values. The welding bead shape is improved and the arc noise is reduced.

Embodiment FIG. 1 shows an embodiment according to the present invention. In the figure, 1 is an input terminal of a power source for welding, 2 is a main transformer section for welding, 3 is a rectifying and smoothing circuit section, 4 is a welding output control element, 5 is a diode for current regeneration, 6 is a reactor, and 7 is a shunt. , 8 is an output terminal of a welding power source, 9 is a contact tip for energization, 10 is a welding wire, 11 is an object to be welded, 12 is a welding current value detection circuit section, 13 is a comparison control circuit section, and 14 is a pulse gradient control. Circuit part,
Reference numeral 15 is an arithmetic circuit unit, and 16 is a welding output fine adjuster.

In Fig. 1, the wire feed rate, which is the welding current, is set by another regulator and is omitted in the figure. However, the operator sets the welding voltage setting value for the wire feed rate by the welding output control unit. The arithmetic circuit unit 15 can read whether the arc length is set to be long or short by using the fine adjustment signal performed by the adjuster 16. With these inputs, the pulse frequency, pulse current, base current, etc. are determined and output, but at the same time, the shorter the arc length is set in accordance with the fine adjustment signal, the more reliable the spray transfer and the pulse trailing part. A steep and large pulse rising slope setting signal and a pulse falling slope setting signal are output to prevent spatter generation due to wire short circuit. On the contrary, as the arc length is set longer, the pulse rising slope setting signal and the pulse falling slope setting signal with a slower and smaller value are output in order to improve the bead appearance and reduce the metallic arc noise.

2A shows an example of input / output signals of the arithmetic circuit unit 15 in the former case and FIG. 2B in the latter case. The arithmetic circuit unit 15 which performs such an operation can be easily realized by a microcomputer or the like. FIG. 3 shows an embodiment in which a microcomputer is used for the arithmetic circuit unit 15.
a is an analog / digital conversion circuit section that also functions as an input port for converting a fine adjustment signal digital signal that is an analog signal into a microcomputer, and 15b is a fine adjustment signal of a digital signal, and a pulse rising slope setting signal according to a fine adjustment value Pulse rising slope output port 15c, pulse falling slope setting signal to the pulse falling slope output port 15d,
The pulse current setting signal is output to the pulse current setting output port 15e which doubles as an output port and a digital / analog converter.
Base current setting output port 15f, which also functions as an output port and digital / analog converter,
The CPU unit outputs a signal for setting the pulse period and the temporal distribution of the pulse unit and the base unit in the pulse period to the output port and the interval timer circuit unit 15g also serving as the timer circuit. A program for realizing this can be easily realized by using the fine adjustment value signal as an address and preliminarily storing the data of the pulse rising slope setting value and the pulse falling slope setting value as a table in the address. 15g is an interval timer circuit consisting of a programmable timer IC. This is also a data table method like the one mentioned above, and it is easy to set an appropriate pulse cycle time and the time distribution of the pulse part and the base part in it by a program. it can. Fifteen
Reference numeral h is a switch element that selects either the pulse current setting signal or the base current setting signal according to the output of the interval timer circuit 15g and outputs it as a current setting value signal. The waveform of FIG. 2 can be realized by the above embodiment.

The current setting value signal, the pulse rising slope setting signal, and the pulse falling slope setting signal output from the arithmetic circuit unit 15 are input to the pulse slope control circuit unit 14, and the rising slope and falling slope shown in FIG. It is output as a current command value signal. The input / output waveforms shown in FIG. 4 are realized in the embodiment shown in FIG. In FIG. 5, 14a and 14b are cross-point switch ICs in which the switch at any of the intersections A to A is turned on by the D input which is a digital signal. An arbitrary series resistance value can be selected by combining this with the resistance values of the resistors 14c and 14d. A CR charging / discharging circuit is formed by this, the diodes 14e, 14f, and the capacitor 14g, and the gradient of the pulse rising portion is 14a, 14c, 14e, 14g, and the gradient of the pulse falling portion is 14b, 14d, 14f, 14g. It is possible to realize the input / output signal waveform as shown in FIG.

The signal of which the welding current value is detected by the shunt 7 is amplified by the welding current value detection circuit unit 12 to a level that can be easily handled by the control circuit, and the current detection value signal is the output from the pulse gradient control circuit unit 14. It is input to the comparison control circuit unit 13 together with the command value, and when it is compared and controlled and the current command value is larger than the current detection value signal, it is sent to the welding output control element 4 as an L level signal and when it is small, an H level signal. Output a control signal. Therefore, the transistor of the welding output control element 4 is turned off when the base terminal input gum is turned on, and turned on when it is high, so that the welding output is feedback-controlled so as to have a waveform equivalent to the current command value signal. The input / output waveforms of the comparison control circuit section 13 in FIG. 5 are as shown in FIG. Note that (a) and (b) of FIG. 5 correspond to (a) and (b) of FIG. As an example for realizing this operation, a commercially available arithmetic comparator can be easily used, and therefore an example of a concrete circuit will be omitted.

The above operation is realized by the above embodiment. Although the chopper method using a transistor is shown as an example of the configuration in FIG. 1, this may be an inverter method, which does not change the gist of the present invention. Further, a welding voltage fine adjuster 16 is shown as means for adjusting the mark length shown in FIG. 1, and a standard welding voltage is automatically set for the wire feed amount. The so-called unified control method is used, but even with a welding power source with an individual control method that sets the wire feed rate and arc length (welding voltage) independently, if the wire material and wire diameter are determined, the wire feed rate will be the standard. Since the voltage can be known and the difference from the set voltage can be calculated, the difference between the unary method and the individual method is not related to the gist of the present invention.

EFFECTS OF THE INVENTION As described above, according to the present invention, in the region of low welding voltage or the region of short arc length including high-speed welding, the rise and fall of the pulse can be automatically set to a steep and large value. As a result, it is possible to ensure the spray transfer and prevent spatter from occurring when the wire is short-circuited. Conversely, in the high welding voltage region or long arc length region, the pulse rise
The fall can be automatically set to a slow and small value, the welding bead appearance can be good and the arc noise is low, and a welding power source with good workability can be provided.

[Brief description of drawings]

FIG. 1 is a block diagram of a power supply for consumable electrode type pulse welding showing an embodiment of the present invention, FIG. 2 is a waveform diagram of input / output signals in an arithmetic circuit section of the power source, and FIG. FIG. 4 is a block diagram, FIG. 4 is an input / output signal waveform diagram in the pulse gradient control circuit section of the power supply, FIG. 5 is a circuit diagram of the pulse gradient control circuit section, and FIG. 6 is an input in the comparison control circuit section of the power supply. It is an output signal waveform diagram.

 ─────────────────────────────────────────────────── --Continued from the front page (56) Reference JP-A-57-112976 (JP, A) JP-A-57-118866 (JP, A) JP-A-62-167085 (JP, A)

Claims (1)

[Claims] 1. A current setting value signal for inputting at least one of a welding voltage and an arc length and alternately setting two values of a current setting value of a pulse current portion and a current setting value of a base current portion, and a base portion. Pulse rising slope setting signal that sets the rising speed of the pulse current when moving from the pulse part to the pulse part, and pulse falling slope setting signal that sets the falling speed of the pulse current when moving from the pulse part to the base part. The arithmetic circuit section for outputting, the current setting value signal, the pulse rising slope setting signal, and the pulse falling slope setting signal are input, and the pulse rising edge is generated when the current setting value signal shifts from the base section to the pulse section. A current command value signal that is a current setting value from the base section to the pulse section is output with a time gradient determined by the gradient setting signal. A pulse gradient control circuit section that outputs a current command value signal that is a current setting value from the pulse section to the base section with a temporal gradient determined by the pulse falling gradient setting signal when transitioning to the base section; Input the command value signal and the current detection value signal from the welding current value detection circuit, compare the current command value and the current detection value, control the welding current value to match the current command value, and output the welding. A comparison control circuit unit for outputting a control signal to a control element, and when the welding voltage is low or the arc length is short, a temporal gradient and the pulse falling gradient setting determined by the pulse rising gradient setting signal When the welding voltage is high or the arc length is long, the pulse rising slope setting signal is set to the pulse rising slope setting signal when the temporal slope determined by the signal is a steep large value. Ri decided is temporal gradient and the pulse fall slopes consumable electrode type pulse welding power source which is a slow small becomes a value temporal gradient is determined by the signal.