JPH0829412B2 - Arc welding machine - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention occurs during welding of an arc welder that automatically feeds a welding wire that is a consumable electrode and transfers wire droplets to a base material that is the object to be welded. The present invention relates to an arc welder capable of reducing the amount of spatter generated.

Conventional technology Conventional technology related to pulse arc welding uses a pulse current generated by the welding machine regardless of the state of the weld, whether the wire is short-circuited with the base metal or the arc is generated without contact. It was applied.

Problems to be Solved by the Invention As described above, in the conventional pulse arc welder, the average welding voltage value is set to be low in order to apply the pulse current at the timing created inside the welder regardless of the state of the welded portion. That is, the welding wire tip does not contact the base metal and all the molten mass at the welding wire tip is sprayed and transferred to the base material (spray transfer), but the welding wire tip contacts the base material. When the probability that the molten mass at the tip of the wire moves to the base material due to the pinch force due to the contact short-circuit current or the surface tension of the molten metal (short-circuit transfer), spatter generation due to the short-circuit transfer increases. This average welding voltage value is set low to increase the welding speed and prevent welding defects such as undercuts, but at the same time, it produces a large amount of spatter and impairs the advantages of low spatter pulse arc welding. Result. In particular, the spatter is generated because the pulse current is applied regardless of the condition of the welded part.
It will be remarkable. This will be described with reference to FIG.

Figures 7a and 7b correspond to the time transition of the welding current waveform of the conventional pulse arc welder and the time transition of the droplet transfer state of the weld when the average welding voltage value including short circuit transfer is set low. Let me show you. In FIG. 7, 9 is a welding wire, 10 is a base metal, 91 is a welding arc, and 92 is spatter. FIG. 7a shows the case where the next pulse current is applied while the welding wire 9 is short-circuited to the base metal 10 and the molten metal is scattered by the spatter 92 at time t ₆ due to the strong pinch force of the pulse current. Short circuit is released. Figure 7b
Is a case where the short circuit is released at time t ₅ immediately before the application of the next pulse current, and the next pulse current is applied before the shape of the molten portion at the tip of the welding wire or the shape of the transferred molten metal becomes needle-shaped. Therefore, a large amount of spatter 92 is generated at time t ₆ due to the pulse current.

The present invention has been made in order to solve the problems of the conventional pulse arc welder, and spatter is generated even when welding with short-circuit transfer mixture is set by setting the average welding voltage low as in high-speed welding. It aims to realize a small number of arc welders.

Means for Solving the Problems In order to solve the above problems, the arc welding machine of the present invention uses a welding wire, which is a consumable electrode, in a contact short-circuit with a base material, which is a workpiece, or when a non-contact arc is being generated. The arc / short circuit determination circuit section that determines whether or not the output is an arc / short circuit determination signal, and the arc / short circuit determination signal as one of the input signals. In the third time period, which is the basic pulse period of the above, the pulse current portion and the base current portion are time-divided and output to indicate the pulse arc welding waveform for spray welding the welding wire and welding, and the contact short circuit is When the first time period is exceeded, a short-circuit transition welding waveform for instructing the welding wire by short-circuiting the welding wire from the time when the first time period has elapsed is instructed, and the predetermined second time period elapses after the contact short circuit is released and an arc occurs. Until the above A dip / pulse control circuit unit that outputs a waveform switching signal that continues to indicate a short-circuit transition welding waveform and a pulse synchronization signal that indicates the time starting point of the pulse current application of pulse arc welding; and the pulse synchronization signal as one of the input signals. One is a pulse waveform circuit section that outputs a time-divided pulse control signal with a pulse current section and a base current section in the third time period, and welding is performed during a contact short circuit using the arc / short circuit determination signal as one of the input signals. Outputs a dip control signal instructing a constant current output according to a predetermined first trajectory that is not faster than the rising speed of the pulse current, and instructing a third welding output control that reduces the welding current during arc generation after arc regeneration. Driving the welding output control element with either the pulse control signal or the dip control signal according to the waveform switching signal. It is made and a switching element to select and input to the drive circuit section.

Action With the above configuration, if there is no contact short circuit for the predetermined first time period or longer, the pulse current and the base current are alternately output by the third time period. If there is a contact short circuit for the first time period or more, the subsequent If the welding output during the contact short-circuit period is controlled to a constant current according to a predetermined first trajectory that is not faster than the rising speed of the pulse current, and the arc is regenerated after the contact short-circuit for the first time period or longer, the arc regeneration time is used as the time starting point to generate the second time. After starting the time period by the number of clocks, if there is no contact short circuit of the first time period or more within the second time period, the third welding output control for decreasing the welding current is performed within the second time period, and then the operation within the third time period. If there is a contact short circuit of the first time period or longer within the second time period, the operation in the case of the contact short circuit of the first time period or longer is repeated.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

In FIG. 1, 1 is an input terminal of an arc welding machine, 2 is a main transformer section, 3 is a rectifying / smoothing circuit section, 4 is a welding output control element, 5 is a reactor, 6 is a shunt, 7 is an output terminal, 8 Is a contact tip for energization, 9 is a welding wire, and 10 is a base material. Reference numeral 11 is a welding current value detection circuit section, and 12 is a welding voltage value detection circuit section.

Reference numeral 13 is an arc / short circuit determination circuit section, which outputs an arc / short circuit determination signal V _AS . A dip / pulse control circuit unit 14 outputs a pulse synchronization signal V _tp and a waveform switching signal V _F2 .

A pulse waveform circuit unit 15 outputs a pulse control signal V _p . A dip waveform circuit unit 16 outputs a dip control signal V _d . A switching element 17 selects either the pulse control signal V _p or the dip control signal V _{d according to} the H or L state of the waveform switching signal and outputs it as a drive signal V _Q. Reference numeral 18 denotes a drive circuit section that drives the welding output control element 4 in response to the drive signal V _Q. In the figure, I _a indicates welding current and V _a indicates welding voltage.

FIG. 2 is a time chart showing the temporal transition of each signal and each output of FIG. 1, and the symbols of the headings of the respective waveforms of FIG. 2 are the signals and outputs of the same symbols described in FIG. Corresponding to.

In the period T _{1 of} FIG. 2, when there is no contact short circuit within the third time period, the arc / short circuit determination circuit unit 13 outputs the H level arc / short circuit determination signal V _AS indicating the arc state. Become. As a result, the dip / pulse control circuit unit 14 outputs the waveform switching signal V _F2 indicating that it is still in the L level pulse welding mode, and also outputs the pulse synchronization signal V _tp instructing the start of pulse current application at time t _10. Then, the third time period, which is the basic pulse period, is counted. The pulse waveform circuit unit 15 determines a predetermined pulse current value, a base current value, and a temporal ratio of the pulse current and the base current within the third time period by the fall of the pulse synchronization signal, and the pulse control signal
Output V _p . Since the switching element 17 indicates that the waveform switching signal V _F2 is in the pulse welding mode, the pulse control signal V _p is selected as the drive signal V _Q and input to the drive circuit section 18. As a result, the welding output control element 4 controls the welding current I _a so as to follow the locus of the pulse control signal V _p .

The period T 2 in FIG. ₂ is a case where there is a minute contact short circuit at the time t ₂₂ of the base current period, and this contact short circuit is the first time period t _p1.
The released naturally in the vibration of the molten portion to an earlier time t ₂₃ for counting completed, a case in which the arc playback. In this case, since the contact short circuit period t _s2 is shorter than the first time period t _{p1, the} waveform switching signal V _F2 remains at the L level instructing the pulse welding mode by the action of the dip / pulse control circuit unit 14, and the pulse synchronizing signal V _tp also counts the third time period t _p3 , which is the basic pulse period, and shifts to the next period T ₃ period. As a result, the following operation becomes the same as that in the T ₁ period.

In the period T _{3 of} FIG. 2, the contact short circuit occurs at time t _32, and the contact short circuit is not released even at time t ₃₃ when the first time period t _p1 has elapsed. ₃₄ shows a case where the contact short circuit is released and an arc occurs, and there is no contact short circuit again within the second time period t _p2 during the subsequent arc generation. In this case, the counting of the third time period t _p3 is interrupted at the time t ₃₃ when the first time period t _p1 has elapsed due to the operation of the dip / pulse control circuit unit 14, and the preparation state for starting the third time period t _p3 by the clock number is set. At the same time, the waveform switching signal V _F2 is switched from the L level to the H level to indicate that the pulse welding mode has been switched to the short-circuit transfer welding (dip welding) mode. As a result, the switching element 17 selects the dip control signal V _d to drive the drive circuit section.
18 and the welding output control element 4 controls the welding output according to the first trajectory at the time of contact short circuit created in the dip waveform circuit unit 16, and after the arc regeneration, during the second time period t _p2 ,
As a result of the third welding output control, the welding current I _a between the times t ₃₃ and t ₄₀ is different from the pulse current portion and the base current portion, and reduces the welding current. The second period
with the t _p2 time t ₄₀ the coincidence complete is the dip pulse control circuit 14 serves the third TU t _p3 between L level constant pulse sync signal V _tp starts counting time period t _p0 of The waveform switching signal V _F2 is changed from the H level to the L level, and an instruction to output from the short-circuit transfer welding mode to the pulse welding mode is output.

Due to the above action, during the second time period after release of the contact short circuit,
By the third welding output control, a molten mass for forming the next droplet transfer is formed at the tip of the wire, and the droplet is separated from the wire in a spray form by the next pulse current applied from time t _40, and one pulse is smoothly performed. 1-drop (transfer) pulse arc welding is continued.

The T ₄ period of FIG. 2 is the time t _{34 of the} T ₃ period until the time t _44.
Same as above, but after that, contact short circuit occurs again at time t ₄₅ during counting of the second time period t _p2 , and again at time t _{32 of the} T ₃ period.
The case where the subsequent operation is performed is shown. In this case, the next contact short circuit occurs at time t ₄₅ without the completion of the clock number of the second time period t _p2 that started counting at time t _44. Therefore, the second time signal V _{tp2 is generated} by the function of the dip pulse control circuit unit 14. Keeps the clock count at L level, and restarts the clock count for the second time period t _p2 again when an arc occurs at time t ₄₇ . Therefore, the waveform switching signal V
_F2 is the time to complete counting the new second time period t _p2 from time t ₄₃
The short-circuit transfer welding mode remains at H level until t ₅₀ , and the pulse synchronization signal V _{tp changes} from time t ₄₃ to the third time period t.
_Suspend the clock count of _p3 and restart the clock count again at time t ₅₀ . As a result, the switching element 17 controls the dip control signal from the time t ₄₃ to the time t _{50 when} the waveform switching signal V _F2 is at the H level.
Since V _d remains selected, the time t
The period from ₄₃ from between and time t ₄₆ to t ₄₄ until t ₄₇ during the welding current I _a next of the first trajectory, from between and time t ₄₇ from the time t ₄₄ to t ₄₆ until t ₅₀ second The welding output becomes welding current I _a and welding voltage V _{a under} the control of No. 3, and a molten mass at the wire tip for the next droplet transfer is formed.

Next, the dip pulse control circuit unit 14 in FIG.
A specific circuit of the above is shown in FIG. In FIG. 3, 140
Is an independent 1st timer circuit unit 141 and 2nd in one IC.
This is a programmable interval timer IC that has three timer circuit units, a timer circuit unit 142 and a third timer circuit unit 143, and sets the operation mode and clock value of each timer circuit unit by the control unit 144. IC. 145 is 1
1st flip-flop circuit unit independent in each IC 146
And a second flip-flop circuit unit 147, which is a general-purpose 7474 type IC, which is an IC having two built-in D-type flip-flop circuit units with a clear preset function. Reference numeral 148 denotes a reference clock signal generation circuit section which outputs the H-level and L-level reference clock signals V _CK at a constant period. An arithmetic circuit unit 149 outputs the operation mode of each timer and the clock numerical value to the programmable interval timer IC 140 according to the welding construction situation. 14A, 14B and 14C are logical product elements, 14D and 14E are logical sum elements, and 14F and 14G are logical inversion elements.

Each timer in the circuit of FIG. 3 is operated by the arithmetic circuit section 149 and the control section 144, and the first timer circuit section 141 uses the G1 terminal input as a start input, and when this input changes from the L level to the H level, the time starts. The signal V _tp1 of L level is started while counting the first time period according to the number of times the signal input from the CLK1 terminal changes from H level to L level, and is at L level during counting of the first time period, and H level during other periods. Performs restartable one-shot timer output from the pin. The second timer circuit section 142 also performs the one-shot timer operation similarly to the first timer circuit section 141. However, since the second timer circuit used in this circuit does not stop the clock even if the G2 input is set to L level during the clock count, the input signal to CLK2 is controlled by the OR element 14E so that the clock count does not advance during the contact short circuit period. Is kept at the H level, the OUT2 output is kept at the L level which is the state during the clock count, and the interrupt function during the clock count is provided so as to restart the clock count at the next arc occurrence. The third timer circuit number 143 counts the number of times the signal from the CLK0 input changes from the H level to the L level when the G0 input is at the H level, and outputs the OUT0 output for a fixed time t _p0 when this rotation reaches a predetermined number. If the G0 input becomes L level, the frequency dividing operation is performed at the L level, and the OUT0 output remains at the H level to interrupt the frequency dividing operation when the G0 input becomes the L level, and the next G0 input returns to the H level. For example, the operation for restarting the frequency division operation is newly performed.

The first flip-flop circuit unit 146 and the second flip-flop circuit unit 147 in the flip-flop IC 147 operate according to the truth value diagram of FIG. Among them, the first flip-flop circuit section 146 keeps the CP1 input and the D1 input at the L level, so that the set-priority RS flip-flop operation using the CLK1 input as the set input and the PR1 input as the reset input is performed. In addition, the second flip-flop circuit unit 147
_Performs an edge-triggered RS flip-flop operation in which the logical product elements 14A and 14B, the logical sum element 14D, and the connection as shown in the figure are used to input the V _F1 signal as a set input and V _tp2 as a reset input. As described above, the circuit of FIG. 3 changes the same state as that of FIG.
As shown in the figure, the result is similar to that of FIG.

The t _p waveform in FIG. 5 is different from the t _p waveform in FIG. 2, but the one-shot pulse generation circuit is used in FIG. 3 by using the rising edge portion of the t _p waveform in FIG. _In addition to the _tp signal,
The output signal of the added one-shot pulse generation circuit is the V _tp signal of FIGS. 1 and 2, and the time limit t of FIG.
The circuit of FIG. 3 realizes a function substantially equivalent to that of FIG. 2 by selecting _p0 so small that it can be ignored in the drawing. Further, the reference clock generation circuit section 148 of FIG. 3 can be easily realized by using a CR oscillation circuit, a crystal oscillator or the like, and therefore its explanation is omitted. Further, the arithmetic circuit unit 149 is a circuit unit using a microcomputer, but its configuration is general-purpose, and a programmable interval timer is used.
The IC 140 is used for setting the operation mode and the count value of each timer of the first timer circuit unit 141, the second timer circuit unit 142, and the third timer circuit unit 143.
The program example is omitted.

In FIG. 1, the arc / short circuit determination circuit unit 13 has _a welding voltage value V _a
Is detected and the value is higher than a predetermined value, arcing occurs, and if it is low, contact short-circuiting operates, which is easily realized by using a comparator. However, since it is commonly used, detailed description is omitted. Further, _a method of directly detecting the arc light instead of detecting the welding voltage value V _a is also conceivable, and any method is included in the present invention.

The dip waveform circuit unit 16 and the pulse waveform circuit unit 15 are also the configurations and operations that are generally used in the conventional welding machine for short-circuit transfer welding and welding machine for pulse arc welding.

The switching element 17 shown in FIG. 1 is also easily realized by a commercially available analog switch IC or the like.

Although the main circuit system is shown as the secondary side chopper system as a configuration example in FIG. 1, this is also included in the present invention as the primary side inverter control system, and the dip pulse control circuit in FIG. 3 is also included. Although a microcomputer was used for the arithmetic circuit section 149 of the section 14, a count value can be set by another method without using it, or a method of counting the number of reference clock pulses in each timer of FIG. , But
This is also included in the present invention even if a CR integrating timer circuit composed of a capacitor and a resistor is used.

The results of measuring the amount of spatter generated by changing the average welding voltage value V _a by the embodiment of FIG. 1 and the circuit of FIG. 3 are the conventional pulse arc welding machine and the conventional short-circuit transfer (MA
G) Fig. 6 shows a comparison with a welding machine.

In FIG. 6, a is the measurement result of the conventional pulse arc welding machine. Further, in FIG. 6, b is a conventional short-circuit transition (MA that performs welding with the welding output waveform as shown in FIG. 8).
G) Welder measurement results.

As can be seen from a and b in FIG. 6, the welding voltage value V _a
In the high temperature range, the pulse arc welding machine, which is a non-contact type droplet transfer system, has a lower spatter, but the difference between a and b becomes smaller as the welding voltage value is lowered due to higher welding speeds. Finally, at a welding voltage lower than the point P, the spatter generation amount reverses and the MAG welding machine becomes lower spatter, and the spatter generation amount of the pulse arc welding machine a increases drastically. This is because the probability of contact short-circuiting increases as described with reference to FIG. 7, and the spatter when releasing this contact short-circuiting with a strong pulse current increases dramatically.

FIG. 6c shows the measurement result of the arc welding machine according to the present embodiment. Since the probability of contact short circuit is low in the region where the welding voltage value V _a is high, the spatter generation amount a is slightly smaller than that of the conventional pulse arc welding machine. It remains in the degree. However, the probability of contact short-circuiting increases at the time of high-speed welding to prevent welding defects such as undercut by lowering the welding voltage value V _a, and it is much less than the spatter generation amount of the conventional pulse arc welder. . In the case of the present embodiment, this is because spray control is selected when there is no contact short circuit, and proper control is selected according to the condition of the weld and short circuit transfer when there is a contact short circuit, and the contact short circuit is released. This is because after that, a molten mass at the tip of the wire for the next droplet transfer is formed.

Note that, in FIG. 6, when the welding voltage value V _a is further lowered, the probability of contact short circuit is extremely high, and it is estimated that the characteristic of c matches the characteristic of b.

EFFECTS OF THE INVENTION As described above, according to the present invention, it is possible to provide an arc welding machine in which the amount of spatter is small even when welding with mixed short circuits is performed by setting a low average welding voltage during high-speed welding or the like.

[Brief description of drawings]

FIG. 1 is a block circuit diagram of an arc welding machine showing an embodiment of the present invention, FIG. 2 is a time chart of signals of the same part, and FIG. 3 is a concrete example of a dip / pulse control circuit part of the arc welding part. FIG. 4 is a circuit diagram, FIG. 4 is a diagram showing a truth value indicating an operation of a main part of the circuit, FIG. 5 is a time chart of signals of the main part, and FIG. 6 is a diagram of the arc welding machine and a conventional arc welding machine. FIG. 7 is a diagram showing a relationship between a welding voltage value and a spatter generation amount, FIG. 7 is a diagram showing a welding current waveform and a droplet transfer state in a time transition of a conventional arc welding machine in association with each other, and FIG. 8 is a conventional short circuit. It is a figure which shows the welding output waveform and the droplet transfer state in time transition of a transfer welding machine correspondingly. 9 ... Welding wire, 10 ... Base metal, 11 ... Welding current value detection circuit section, 12 ... Welding voltage value detection circuit section, 13 ... Arc / short circuit judgment circuit section, 14 ... Dip / pulse control Circuit part, 15 ... pulse waveform circuit part, 16 ... dip waveform circuit part, 17 ... switching element, 18 ... drive circuit part.

Claims (4)

[Claims] 1. An arc / short circuit which outputs an arc / short circuit determination signal by determining whether a welding wire, which is a consumable electrode, is in contact with the base material, which is the object to be welded, is short-circuited or an arc is being generated without contact. A determination circuit unit and a pulse current unit and a base current unit within a third time period, which is a predetermined basic pulse period when a contact short circuit is a predetermined first time period or less, using the arc / short circuit determination signal as one of input signals. The pulse arc welding waveform for spraying and transferring the welding wire by welding is indicated by and, and when the contact short circuit is the first time period or more, the welding wire is started from the time point of the first time period. A waveform switching signal that indicates a short-circuiting transition welding waveform that causes short-circuiting transition and welding, and continues to instruct the short-circuiting transition welding waveform until a predetermined second time period elapses after the contact short-circuit is released and an arc occurs.
A dip pulse control circuit unit that outputs a pulse period signal that indicates the time starting point of the pulse current application of pulse arc welding, and the pulse synchronization signal as one of the input signals,
A pulse waveform circuit section that outputs a pulse control signal that is time-divided with the pulse current section and the base current section in the third time period; and the welding output is pulsed during the contact short circuit with the arc / short circuit determination signal as one of the input signals. A dip waveform that outputs a dip control signal that directs a constant current output according to a predetermined first trajectory that is not faster than the current rising speed, and that commands a third welding output control that decreases the welding current during arc generation after arc regeneration. An arc welding machine comprising a circuit section and a switching element for selecting and inputting either the pulse control signal or the dip control signal to a drive circuit section for driving a welding output control element according to the waveform switching signal. . 2. The dip / pulse control circuit section uses as input signals a reference clock signal that repeats a state change at a constant cycle and the arc / short circuit determination signal, and a time starting point is a time point when a contact short circuit occurs due to an arc occurrence. Start counting the first time period according to the number of state changes of the reference clock signal,
Input a first timer circuit section that changes the state to L level while counting the first time period and H level during the other period and outputs the first time period signal, the reference clock signal, and the arc / short circuit determination signal The second time period is counted according to the number of times the state of the reference clock signal changes, starting from the time when an arc occurs from a contact short circuit as a signal, and is at the L level while the second time period is counting, and other periods. Input a second timer circuit section that outputs a second timed signal while changing the state to the H level and can be restarted while counting the second timed period, the first timed signal, and the arc / short circuit determination signal. As a signal, a first flip-flop signal which changes the state to L level when the occurrence of arc is changed to contact short circuit, and when the contact short circuit completes counting the first time period and is still in the contact short circuit state, outputs the first flip flop signal. To a first flip-flop circuit, the first and the flip-flop signal to the second Timed signal and an input signal, said first flip-flop signal H
A first timer circuit section which starts counting a first time period when the level is changed to L level while counting the first time period, and changes the state to H level during other periods and outputs a first time period signal;
The reference clock signal and the arc / short circuit determination signal are used as input signals, and the second time period is started to be counted according to the number of state changes of the reference clock signal with a time starting point when an arc occurs from a contact short circuit, A second timer circuit section that changes the state to L level during counting of the second time period and outputs the second time period signal while changing to the H level during the other time period, and is capable of restarting operation even while counting the second time period; The first time limit signal and the arc / short circuit determination signal are used as input signals, and the level is L when the contact is short-circuited from the occurrence of an arc, and H is the contact short circuit state when the contact short circuit has completed counting the first time period. A first flip-flop circuit section that outputs a first flip-flop signal that changes between a level and a state, and the first flip-flop signal and the second time limit signal as input signals, A second flip-flop circuit section that outputs a second flip-flop signal that changes its state to an H level when the second flip-flop signal has finished counting the second time period, and a second flip-flop signal that changes its state to an L level when the second flip-flop signal has completed counting the second time period. And using the second flip-flop signal and the reference clock signal as input signals, and when the second flip-flop signal becomes L level, counting the third time period is started according to the number of state changes of the reference clock signal. The output of the third time limit signal is repeated by changing the state to L level for a certain period of time when the counting of the third time period is started, and to H level for the other period, so that the second flip-flop signal becomes H level. And a third timer circuit section that is in a ready state to start counting the third time period while keeping the third time signal at the H level. Arc welder of the claims paragraph 1, wherein the output as the waveform switching signal to the second flip-flop signal to output as said pulse synchronization signal. 3. The third welding output control is substantially constant voltage characteristic control or constant current control according to a predetermined second locus. Two
The arc welder according to the item. 4. The first time period, the second time period, the first locus, and the third welding output control include welding wire feeding speed, average welding voltage setting, welding speed, welding wire material, and welding wire. The arc welding machine according to claim 1, 2 or 3, which is a function of any one of the diameter and the component composition ratio of the shield gas, or a plurality of functions.