JPH0580308B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a consumable electrode arc welding method and apparatus for welding by bringing the tip of a consumable electrode into contact between objects to be welded and starting an arc.

(b) Prior art There are mainly two types of conventional consumable electrode arc welding methods and devices in which the tip of a consumable electrode (hereinafter referred to as a wire) contacts the workpiece to start the arc and weld. .

First, the first method is to apply a predetermined limited arc start current for a predetermined time depending on the welding conditions at the time of arc start, and
A predetermined limited arc starting current Ip selected corresponding to at least one of the diameter of the consumable electrode (hereinafter referred to as wire diameter) and the welding current value is applied for a predetermined time Tp as shown in FIG. ing.
In this first method, the peak value of the arc starting current is limited to Ip, so there is less spatter when starting the arc, and there is also less change in current from a short circuit to the arc, so the arc when starting the arc is It has the advantage of being easily stabilized. but,
On the other hand, the time from when the arc is extinguished by the end of arc welding work until the arc is generated by starting the arc again (hereinafter referred to as arc rest time)
It is called T ₀ . ) The temperature at the tip of the wire varies depending on the size of
Even if Tp is controlled, the arc pause time T ₀ changes significantly, and when T ₀ is small, a burnback phenomenon occurs in which the wire melts to the vicinity of the chip, and conversely, when T ₀ is large, the wire melts close to the tip. There was a drawback that a sticking phenomenon occurred in which the tip of the wire was welded.

Next, in the second method, if the arc pause time T ₀ exceeds a certain time, at least one of the wire feeding speed and the output voltage E of the welding power source when starting the arc again as shown in FIG. It's so big. This second method has the advantage that burnback and stagnation phenomena are less likely to occur depending on the magnitude of the arc pause time T ₀ . However, on the other hand, the peak value of the arc starting current is not controlled to a predetermined value, so the peak value fluctuates, causing spatter and delaying the stability of the arc at the time of starting. It was hot.

(C) Problems to be Solved by the Invention By solving the conventional problems, the welding method and device of the present invention eliminates the stagnation phenomenon and the burnback phenomenon regardless of the length of the arc pause time, and the welding method and device of the present invention To provide a consumable electrode arc welding method that is easy to start, quickly stabilizes the arc, and generates extremely little spatter when starting the arc.

(d) Means for Solving the Problems In order to solve the above problems, the welding method of the present invention solves the above-mentioned problems by controlling the welding method from the time when the arc is extinguished by the end of the arc welding operation until the time when the arc is generated by starting the arc again. As the arc pause time T ₀ increases, the peak value Ip of the arc start current, the conduction time Tp of the arc start current, or the product Ip×Tp of the peak value Ip of the arc start current and the conduction time Tp of the arc start current increase. A consumable electrode arc welding method is proposed.

Further, a second invention provides a consumable electrode arc welding method in which the tip of a consumable electrode is brought into contact between objects to be welded, and a preset arc start current is applied for a predetermined period of time to start the arc. The arc occurrence/extinction detection circuit 8 detects the extinction point and outputs a signal, and the arc pause time is determined by measuring the time from when the arc occurrence/extinction detection circuit 8 outputs the arc extinction signal until it outputs the arc occurrence signal again. Signal S
an arc pause time measuring circuit 11 that outputs 11;
Signals are set and stored in advance in correspondence with the length of the arc rest time _T0 , and the start current is selected from the preset signals according to the length of the arc rest time signal S11 output from the arc rest time measurement circuit 11. A read-only storage device (JIS C 6230 12.05.09) (hereinafter referred to as a memory selection circuit) that outputs a setting signal S12, and an arc generation/extinction detection circuit 8
A start current energization time setting circuit 13 outputs a start current energization time signal S13 for a period determined corresponding to the start current setting signal S12 from the time when the output signal is input, and a start current energization time setting circuit 13 sets The start current peak value setting circuit 14 sets the peak value Is of the start current to be applied during the period in which the arc start current Is is applied while the start current application time signal S13 is output, and the start current application time signal S13
The present invention provides a consumable electrode arc welding device equipped with an output current switching circuit 15 that switches to a steady state welding current when the output of the welding current stops.

Furthermore, a third invention is a consumable electrode arc welding device that starts an arc by bringing the tip of a consumable electrode into contact between objects to be welded and applying a preset arc start current for a predetermined period of time. The arc occurrence/extinction detection circuit 8 detects the extinction point and outputs a signal, and the arc pause time is determined by measuring the time from when the arc occurrence/extinction detection circuit 8 outputs the arc extinction signal until it outputs the arc occurrence signal again. Signal S
an arc pause time measuring circuit 11 that outputs 11;
Signals are set and stored in advance in correspondence with the length of the arc rest time _T0 , and the start current is selected from the preset signals according to the length of the arc rest time signal S11 output from the arc rest time measurement circuit 11. a memory selection circuit 12 that outputs a setting signal S12; a start current energization time setting circuit 13 that outputs a start current energization time signal S13 for a preset time from the time when the output signal of the arc generation/extinction detection circuit 8 is input; The memory selection circuit 1
a start current peak value switching circuit 16 that selects and switches a start current peak value setting signal S16 according to a start current setting signal S12 output from 2;
and an output current switching circuit 15 that supplies the arc start current Is while the start current energization time signal S13 is output, and switches to the steady state welding current when the output of the start current energization time signal S13 stops. An electrode arc welding device is provided.

(e) Effects The effects of the welding method of the present invention will be explained below with reference to the drawings.

FIG. 2 is a diagram showing the relationship between elapsed time T (horizontal axis) after arc start and wire feeding speed V (vertical axis) or output current value I (vertical axis). In the figure, when the torch switch SW is pressed at time T ₁ and the wire is fed at a substantially constant wire slowdown speed Vs, the wire comes into contact with the workpiece at time T ₂ and a preset arc start current Ip flows. . After the arc is generated by applying this arc start current, after a preset time Tp has elapsed, the arc start current Ip is switched to the steady state welding current Io and wire feeding speed Vo to continue the arc welding work. When the wire feeding is stopped and the arc is extinguished upon completion of the arc welding work, the wire tip is moved by a distance Le (hereinafter referred to as extension) from the tip tip 3e in the welding torch 3, as shown in Fig. 3. Stop in a protruding position. Upon completion of this arc welding work, as shown in Fig. 4, the temperature of the molten ball 4e at the tip of the extension, that is, the amount of heat Q (vertical axis) possessed by the molten ball, changes over the elapsed arc rest time T ₀ (horizontal axis). For example, when the arc pause time is short and T ₀ = Ts, the retained heat quantity is as large as Q = Q ₁ , but when the arc pause time is long and T ₀ = Tl, the retained heat quantity decreases exponentially. Q=
Q ₂ will be small.

Here, the arc pause time T ₀ from the time the arc is extinguished by the end of the arc welding work until the arc is generated again by the arc start, and the time required to obtain a good arc start without burnback or stagnation of the wire tip. The arc start conditions, that is, the relationship between the arc start current Ip and the current conduction time Tp will be discussed.

In Fig. 5, the wire feeding speed V at arc start is kept constant, and the arc rest time T ₀
(horizontal axis), the product Ip of the arc start current Ip that provides a good arc start, and its energization time Tp
It is a figure which shows the relationship with xTp (vertical axis). In the figure, the diagonally shaded area surrounded by curve _A1 and curve _A2 is the area where a good arc start without burnback or stepping can be obtained. In addition, the curve
A ₀ is the curve at which a good arc start can be obtained, curve A ₁ is the upper limit at which a good arc start can be obtained, and above this the wire tip burns back, and curve A ₂ is at the lower limit. In this case, the wire tip will become stuck below this point.

Examining Fig. 5, when the arc rest time T ₀ is short, for example, T ₀ = 2 [seconds], the product of the arc start current Ip and its energization time Tp is 800.
Although it is small (ampere-second), the arc rest time
If T ₀ is long, for example T ₀ = 10 seconds, Ip
The product with Tp is as large as 3200 [ampere-seconds]. Furthermore, as T ₀ becomes larger, the product for increasing time T ₀ becomes
The increase in Ip×Tp becomes smaller and approaches a constant value.

Based on the above study results, the welding method of the present invention will be explained with reference to FIG. In the figure, the horizontal axis represents the elapsed time T of the welding operation, and the vertical axis represents the "ON" or "OFF" state of the torch switch SW, the wire feeding speed V, and the output current value I, respectively, from the top. At time T ₁ , the torch switch SW
When turned on, the wire slows down at a low speed Vs and when it comes into contact with the workpiece, the arc starts. At time T ₂ , turn on the torch switch SW.
When turned OFF, the wire feeding speed decreases rapidly, the arc length increases, and the arc disappears. this
The arc suspension time T ₀ is measured from time T ₂ until time T ₃ when the arc is generated again and welding work is started. Hereinafter, the welding method of the present invention is as follows.

When keeping the peak value Ip of the arc start current at a preset approximately constant value.

When the arc pause time is short T ₀ = Ts, the arc start current conduction time Tp = Tps is shortened, and when the arc pause time T ₀ becomes large like Tl, the arc start current conduction time T ₀ is increased. do.

When keeping the arc start current conduction time Tp at a preset approximately constant value.

When the arc rest time is short and T ₀ = Ts, the peak value of the arc start current is shortened to Ip = Ips,
When the arc pause time T ₀ becomes large like Tl, the peak value Ip of the arc start current is increased.

As the arc pause time T ₀ increases, the product Tp×Ip of the arc start current conduction time Tp and the arc start current peak value Ip is increased.

(F) Embodiment FIG. 6 shows an embodiment of the welding apparatus of the present invention.
In the figure, 1 is a welding power source used in the normal consumable electrode arc welding method, 2 is a wire feeding device, 3 is a welding torch, 4 is a wire, 5 is a workpiece, and 6 is the tip of the wire. 7 is a wire feeding control circuit. 8
1 is an arc occurrence/extinguishment detection circuit that detects the time of arc occurrence and the time of arc extinction and outputs a signal, and includes a welding current detection circuit, an arc light output circuit, etc. 9 is a welding current setting circuit for setting a normal welding current value, and when the welding power source 1 has constant voltage characteristics, the welding current value can be changed by changing the set value of the wire feeding speed. can.

11a is a clock signal generation circuit, and 11b is a counter which measures the number of clock pulses set by the arc extinction signal of the arc occurrence/extinction detection circuit 8 until the arrival of the arc occurrence signal and outputs the number of clock pulses to the latch circuit 11c. is reset by the signal output after confirming the input signal. The latch circuit 11c has an arc pause time T ₀
The number of clock pulses of the counter 11b corresponding to the number of clock pulses is outputted to a memory selection circuit 12, which will be described later.

11 measures the time from when the arc extinguishment detection circuit 8 outputs the arc extinguishment signal until it outputs the arc occurrence signal again, and generates an arc pause time signal S1.
The arc rest time measuring circuit 1 outputs the signal 1, and the arc rest time measuring circuit 12 has signals set and stored in advance in correspondence with the length of the arc rest time _T0.
a memory selection circuit that selects from preset signals according to the length of the arc pause time signal S11 output from 1 and outputs the start current setting signal S12;
13 is a start current energization time setting circuit that outputs a start current energization time signal S13 for a period determined in accordance with the start current setting signal S12 from the time when the output signal of the arc generation/extinction detection circuit 8 is input; 14 is a start current energization time setting circuit; a start current peak value setting circuit that sets the peak value Is of the start current that is energized during the period set by the time setting circuit 13;
15 is an output current switching circuit that passes arc start current Is while the start current energization time signal S13 is being outputted, and switches to a steady state welding current when the output of the start current energization time signal S13 is stopped; 16 is a memory selection circuit 12 21 is a wire diameter setting circuit, 22 is a wire material setting circuit, and 23 is a welding method setting circuit. , 24 is an A/D converter that converts the analog signal set by the welding current setting circuit 9 into a digital signal and supplies the digital signal to the memory selection circuit 12.

The operation of the welding apparatus of the present invention will be described below with reference to FIGS. 6 to 8.

First, the relationship between each setting circuit in FIG. 6, the address map in FIG. 7, and the diagram showing the operation of the start current peak value switching circuit in FIG. 8 will be explained.

The arc rest time measuring circuit 11 in FIG. 6 outputs to the memory selection circuit 12 the number of clock pulses corresponding to the arc rest time T ₀ from the point of extinction of the arc to the point of time when the arc occurs again. Accordingly, for example, as shown in Fig. 7, very short "SS", short "S", medium "M", long "L",
Address A of circuit 12, divided into extremely long "LL"
A signal of 1 or 0 is given to signals 8 to A10. Furthermore, when the wire diameter is set in the wire diameter setting circuit 21, the wire diameter is 1.0, as shown in FIG.
Address A6 of circuit 12 depending on 1.2 or 1.6mm
A signal of 1 or 0 is given to and A7. Similarly, when the wire material is set in the wire material setting circuit 22, as shown in FIG. 7, the circuit 1
When 0 or 1 is given to the address A5 of No. 2 and the welding method is set in the welding method setting circuit 23, the welding method is set in the welding method setting circuit 23.
As shown in the figure, the welding method is carbon dioxide arc welding.
Address A4 of circuit 12 is given a 0 or 1 depending on CO ₂ or MAG welding. Furthermore, when the welding current value is set in the welding current setting circuit 9, the A/
The signal is converted into a 4-bit digital signal by the D conversion circuit 24 and applied to addresses A0 to A3 of the circuit 12. The memory selection circuit 12 has an address A.
When each of the above-mentioned signals is input to 0 to A10, a preset signal is selected for each signal and the addresses D0 to D of the memory selection circuit 12 are selected.
3, a start current setting signal S12 is output. The start current peak value switching circuit 16 selects addresses D0 to D of the memory selection circuit 12.
As shown in FIG. 8, the start current peak values I1 to I4 set by the start current peak value setting circuit 14 are determined by the upper two bit signals D2 and D3 of the four bit signals output from the start current peak value setting circuit 14. Now you have to choose one.

In the welding apparatus of the present invention configured as described above, a welding start switch (not shown) causes the welding power source 1 to supply between the output wire 4 and the workpiece 5, and the wire feeding device 2 to feed the wire 4. Then, the tip of the wire contacts the workpiece 5, an arc 6 is generated, and a welding current flows. Arc generation/extinction detection circuit 8 detects welding current or arc 6 and supplies an arc generation signal to arc pause time measurement circuit 11 . The counter 11b supplies a measured value of the number of clock pulses from supplying power to the welding power source 1 to supplying the arc generation signal to the memory selection circuit 12 through the latch circuit 11c. In the case of the first arc start, since it takes a long time from the time when power is applied to the welding power source 1 until the arc start, the signals supplied to addresses A8 to A10 of the memory selection circuit 12 are The length becomes ``LL''. A start current energization signal S12 is output from addresses D0 to D3 of the circuit 12 by selecting a condition stored in advance in the storage selection circuit 12 from this condition and signals supplied from other circuits 21 to 24. This signal S12 operates in the following three ways.

The first case is a case where the start current conduction time is controlled by controlling only the set time of the start current conduction time setting circuit 13, that is, the on-delay timer, depending on the length of the signal S12, that is, the arc pause time. In this first case, the start current peak value switching circuit 16 is not controlled by the signal from the circuit 12, but is controlled by one type of setting or a plurality of settings according to the fixed or manual settings set in the start current peak value setting circuit 14. The value can be changed manually. Here, when the arc starts, the start current peak value selection signal S16 set by the start current peak value switching circuit 16 is supplied from the contact A of the output current switching circuit 15 to the wire feeding control circuit 7,
The wire feeding device 2 is controlled at the wire feeding speed determined by the setting signal S16, and a start current having a predetermined peak value is applied. On the other hand, the start current energization time setting circuit 13 starts the start current energization time setting circuit 13 after a time corresponding to the start current setting signal S12 output from the circuit 12.
operates, and the start current energization time signal S13
is supplied to the output current switching circuit 15, and the circuit 15
Switch the contact from A to B. Through this operation, the starting current value is switched to the normal welding current set by the welding current setting circuit 9, and the arc welding operation is continued. When the arc is extinguished upon completion of the arc welding work, the arc occurrence/extinction detection circuit 8 outputs an arc extinguishment signal to the arc cessation measuring circuit 11. The counter 11b measures the number of clock pulses by inputting this arc extinction signal. When an arc is generated again by starting arc welding work, the arc generation/extinction detection circuit 8 supplies an arc generation signal to the circuit 11, and the latch circuit 11c supplies the number of clock pulses measured by the counter 11b to the memory selection circuit 12. .
The circuit 12 selects addresses D0 to D3 from the set values stored in the circuit 12 in advance, depending on the number of clock pulses, that is, the length of the arc pause time.
Output a signal from. The following operation repeats the same operation as explained at the first arc start.

The second operation of the start current setting signal S12 output from the memory selection circuit 12 is as follows.
Since the setting time of the start current energization time setting circuit 13 does not change within a preset constant time, the start current peak value switching circuit 16 is used instead.
However, this is a case where the start current peak is selected and switched by the start current setting signal S12 outputted by the memory selection circuit 12. This circuit 16 is
As shown in FIG. 8, the upper 2 bits of the 4-bit start current setting signal S12 cause
Depending on the length of the arc pause time, that is, the signal of the upper 2 bits, the start current peak value signals _I1 to _I4 set in the start current peak value setting circuit 14 are selected and supplied to the contact A of the output current switching circuit 15. . The operations of other circuits other than the start current energization time setting circuit 13 and the start current peak value switching circuit 16, such as arc generation, arc extinction, and arc generation again, are the same as in the case of .

The third operation of the start current setting signal S12 output from the memory selection circuit 12 is as follows.
The setting time of the start current energization time setting circuit 13 is controlled by S12 as in the case of
And the start current peak value switching circuit 16 also includes:
It is controlled by the signal S12 in the same way as in the case of .
To summarize the above differences, depending on the length of the arc pause time, that is, the start current energization signal S12 output from the memory selection circuit 12,
In the case of , the start current conduction time circuit 13 controls only the conduction time of the start current of a preset constant peak value, and in the case of
The energization is controlled by selecting and switching the peak value of the start current, and in the case of , both the start current energization time and the peak value of the start current are controlled.

As described above, in the apparatus for implementing the welding method of the present invention, the circuits 21 to 24 may be omitted or may be partially replaced with other setting circuits, and the input/output signals of the memory selection circuit 12 may also be used in the embodiments. Any selection may be made without limitation as long as any one of the above conditions is satisfied. Further, as the circuit components, a dedicated circuit for each circuit may be used, and a microcomputer program may be used to perform the same operation as each dedicated circuit.

(g) Effects of the invention When welding is performed using the welding method and welding device of the present invention, the "arc suspension time" from the time when the arc disappears due to a pause in arc welding work to the time when the arc is generated when arc welding work is restarted is measured, By controlling at least one of the conduction time of the arc start current and the peak value of the start current according to the length thereof, melting of the wire tip at the time of arc start can be achieved without being affected by the length of the "arc pause time". By optimizing the conditions, it is possible to prevent interruption of arc welding work due to burnback, stagnation, etc., and to prevent welding defects from occurring.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the relationship between elapsed time T (horizontal axis) and welding current value I (vertical axis) in the welding method of the present invention, and FIG. Figure 3 is a diagram showing the relationship between wire feeding speed V (vertical axis) and welding current value I (vertical axis); Figure 3 is a diagram showing the state of the wire tip after arc welding work is completed; The figure shows the relationship between the arc rest time T ₀ (horizontal axis) and the amount of heat Q held by the molten ball at the tip of the wire (vertical axis). Figure 5 shows the relationship between the arc rest time T ₀ (horizontal axis) and The product Ip×Tp of the arc start current Ip and its energization time Tp to obtain a good arc start
(vertical axis), FIG. 6 is a diagram showing an embodiment of an apparatus for carrying out the welding method of the present invention, and FIG.
The figure shows an address map of the memory selection circuit of Fig. 6, Fig. 8 shows an example of the operation of the start current peak value switching circuit of Fig. 6, and Fig. 9 shows the start of the conventional welding method. FIG. 10 is a diagram showing the first conventional example showing the relationship between the elapsed time T (horizontal axis) and the welding current value I (vertical axis), and FIG. 10 shows the elapsed time T and arc pause time T of the conventional welding method. ₀ (horizontal axis), wire feeding speed V, and output voltage E of a welding power source (vertical axis) in a second conventional example. 1... Welding power source, 2... Wire feeding device, 3
...Welding torch, 4...Consumable electrode (wire),
5... Workpiece, 6... Arc, 7... Wire feeding control circuit, 8... Arc generation/extinction detection circuit, 9
... Welding current setting circuit, 11 ... Arc pause time measurement circuit, 12 ... Memory selection circuit, 13 ... Start current energization time setting circuit, 14 ... Start current peak value setting circuit, 15 ... Output current switching circuit , 16... Start current peak value switching circuit, 2
1... Wire diameter setting circuit, 22... Wire material setting circuit, 23... Welding method setting circuit, 24...
A/D conversion circuit.

Claims (1)

[Claims] 1. Bringing the tip of the consumable electrode into contact between the objects to be welded,
In a consumable electrode arc welding method in which the arc is started by applying a preset arc start current for a predetermined period of time, the arc pause time T ₀ is the time from when the arc is extinguished by the end of arc welding work until the arc is generated again by arc start. The arc start current peak value Is or the arc start current conduction time Ts or the arc start current peak value Is and the arc start current conduction time increase as the arc pause time T ₀ increases.
A consumable electrode arc welding method that increases the product Is×Ts with Ts. 2. Touch the tip of the consumable electrode between the objects to be welded,
In a consumable electrode arc welding method in which an arc is started by applying a preset arc start current for a predetermined period of time, an arc occurrence/extinguishment detection circuit 8 detects the point of arc generation and the time of arc extinguishment and outputs a signal; Arc pause time measuring circuit 1 that measures the time from when the detection circuit 8 outputs the arc extinction signal until it outputs the arc occurrence signal again and outputs the arc pause time signal S11.
1 and a signal is set and stored in advance in correspondence with the length of the arc rest time _T0 , and the signal is selected from the signals set in advance according to the length of the arc rest time signal S11 outputted from the arc rest time measurement circuit 11. and a memory selection circuit 12 that outputs a start current setting signal S12, and a start current energization time signal for a time determined corresponding to the start current setting signal S12 from the time when the output signal of the arc generation/extinction detection circuit 8 is input. A start current energization time setting circuit 13 that outputs S13, a start current peak value setting circuit 14 that sets a peak value Is of the start current to be energized during the period set by the start current energization time setting circuit 13, A consumable electrode arc welding device comprising an output current switching circuit 15 that supplies an arc start current Is while an energization time signal S13 is output, and switches to a steady state welding current when the output of the start current energization time signal S13 stops. . 3. Touch the tip of the consumable electrode between the objects to be welded,
In a consumable electrode arc welding device that starts an arc by applying a preset arc start current for a predetermined period of time, the arc welding device includes an arc occurrence/extinguishment detection circuit 8 that detects the point of arc generation and the time of arc extinction and outputs a signal; Arc pause time measuring circuit 1 that measures the time from when the detection circuit 8 outputs the arc extinction signal until it outputs the arc occurrence signal again and outputs the arc pause time signal S11.
1 and a signal is set and stored in advance in correspondence with the length of the arc rest time _T0 , and the signal is selected from the signals set in advance according to the length of the arc rest time signal S11 outputted from the arc rest time measurement circuit 11. a memory selection circuit 12 that outputs a start current setting signal S12, and a start current energization time that outputs a start current energization time signal S13 for a preset time from the time when the output signal of the arc generation/extinction detection circuit 8 is input. A setting circuit 13, a start current peak value switching circuit 16 that selects and switches a start current peak value setting signal S16 according to a start current setting signal S12 outputted from the memory selection circuit 12, and a start current energization time signal S13. Arc start current while being output
A consumable electrode arc welding device comprising an output current switching circuit 15 that energizes Is and switches to a steady state welding current when the output of a start current energization time signal S13 is stopped. 4. The consumable electrode according to claim 3, wherein the start current energization time setting circuit 13 is a circuit that selects and outputs the start current energization time according to the start current setting signal S12 output from the memory selection circuit 12. Arc welding equipment.