JPS5841949B2 - Automatic welding method using coated arc welding rod and its control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION In automatic welding using coated arc welding rods, this invention connects a large number of coated arc welding rods to one welding machine,
The present invention relates to an automatic welding method and a control device thereof, which are capable of automatically welding long distances unattended by igniting these in sequence.

Typical coated arc welding rods include gravity welding rods, manual welding frames, and horizontal welding rods. Among these,
Gravity welding rods and horizontal covered arc welding rods with processed tips can be ignited simply by applying voltage if the welding jig is set so that the tip of the welding rod is in contact with the welding base metal. Welding is performed using a single welding rod without the intervention of an operator.

The present invention uses such a coated arc welding rod and uses a single welding machine to process a large number of coated arc welding rods, welding jigs,
Automatic welding can be performed by simply setting the cables and control device, and the worker can leave the site, reducing the worker's exposure to high temperatures and inhaling fumes, greatly improving the working environment. This will improve work efficiency.

The details of this invention will be described below, but in order to avoid complicating the explanation, a horizontal type covered arc welding rod will be taken as an example.

It goes without saying that the present invention is not limited to the horizontal type.

FIG. 1 is an explanatory diagram of the automatic welding method of the present invention.

The welding machine W used is a general arc welding machine, and the current-voltage characteristics exhibit characteristics called constant current characteristics or drooping characteristics.When the load changes from a no-load state to an arc state or a short-circuit state, the welding machine W The output voltage fluctuates greatly.

Control circuit C1tC2j for this welding machine WKn...
....

Connect Cn in parallel.

Each control circuit C1, C2, . . . , Cn has a timer function A1. A2゜・・・・・・・・・
, An, electric circuit opening/closing function B1. B2.・・・・・・・・・
.

Bn, short circuit prevention function, B2.・・・・・・・・・
, Dn, and memory function E1. B2.・・・・・・
..., En, and control circuits C□, c2
．． . . . Cn operates only with the power supplied from the welding machine W, and there is no need to connect other control signal lines.

These n control circuits C1, C2,...
, Cn timer function A, , A2.・・・・・・・・・
, An are set to have different operating times, that is, the time from when the timer is excited and starts timing until it outputs a specific signal, such as a contact signal, to the outside. The built-in control circuits are numbered C1, C2, . . . , Cn in order.

These control circuits C1, C2, ......, C
, m welding jigs L-1, L-2,...
...°, 1-m, 2-1, 2-2,...
......, 2-m.

nLn2+..., nm are connected in parallel, and one horizontal covered arc welding rod P is connected to each welding jig.

However, the tip of each welding rod P is placed so as to touch the end of the other welding rod P, and the first welding rod y has a tip processed F.
is being carried out.

After arranging the equipment as described above, the switch of the welding machine W is turned ON, and the output voltage of the welding machine W is set to the n control circuits C1,
C2,......Add to Cn.

The timer functions A in each control circuit C start timing at the same time, but the timer with the shortest operating time, that is, the control circuit C1
The timer first operates to close the electric circuit in the control circuit C1, and the input voltage of the control circuit C1 is output, and the m welding jigs 1-1, 1-2.・・・・・・・・・
, 1-m are applied with the output voltage of the welding machine W.

Then, the welding rod y whose tip has been processed F is short-circuited to the grounded base metal through the tip processing portion, and the tip processing portion becomes red hot and then shifts to an arc state.

Thereafter, m welding rods connected to the control circuit C1 are sequentially arc-welded.

Note that at the time when the welding rod P' short-circuits to the base metal, the other control circuits C2, .

The timer in Cn is reset on the short-circuit drop in supply voltage.

Also, during arc welding, the voltage across the timer is an arc voltage that is significantly lower than the no-load voltage, and the timer will not operate at this voltage.

In this way, when all m welding rods connected to the control circuit C1 are melted and this series of welding is completed, all the welding jigs 1-1. connected to the control circuit C1 are melted.
......, no current flows from 1-m to the base metal, and the output voltage of the welding machine W rises to the no-load voltage.

Therefore, all the timers in each control circuit C, except for the timer in the control circuit C1, start timing at the same time.

The timer function A1 in the control circuit C1 is the same as the control circuit C0.
The memory function E in the welding machine remembers what has worked once, and the time will not be counted again unless the output of the welding machine W is released once.

After the timers in each circuit from the control circuit C2 to the control circuit Cn start timing at the same time, the electric circuit in the control circuit C2 containing the timer with the shortest operating time is closed.

Thereafter, similar to the control circuit C1 series, the control circuit C2 series is also arc welded, and then the control circuits C3 and C4 are sequentially welded.
, . . . , welding is automatically performed up to the Cn series.

Therefore, once the welding machine W is turned on, welding of HXm welding rods P connected to one welding machine W will be performed automatically and unattended.

In addition, if the transition from the short-circuit state to the arc state does not go well in the tip processing part, that is, if the short-circuit state continues for a long time due to failure in ignition, or if a short-circuit accident occurs in the electric path from control circuit C to the welding rod. If this occurs, the short-circuit prevention circuit in each control circuit C operates to open the circuit, and no voltage is applied to that series again.

The automatic welding method of the present invention has been described above, and the control circuit C will now be described in detail.

FIG. 2 is an external view of the control circuit C.

The control circuit C is housed in a box G, and externally there is a female input terminal H that connects the electric circuit to the welding jig side, and a cable J.
A male output terminal for connecting an electric circuit to the welding machine W side and a ground plate Q are exposed at its tip.

FIG. 3 is a wiring diagram of the control circuit C.

The part surrounded by the broken line is housed in the control box G.

In this circuit diagram, Ti (where i is a number from 1 to n assigned to the control circuit) is a delayed release type timer, Ki is a delayed release type auxiliary relay, and Ri is a delayed release type magnetic contactor. is connected to the output terminal H via the main contact Ri2, which is the a contact of the electromagnetic contactor Ri, and the series circuit of the timer Ti and the b contact Ki2 of the auxiliary relay Ki, and the 1st a contact Til of the auxiliary relay Ki and the timer Ti are connected to the output terminal H. and the series circuit of the electromagnetic contactor Ri and the second a contact Ti2 of the contact 1Ti are connected to the input terminal RI and the ground plate Q, respectively.
The a-contact Kil of the auxiliary relay Ki is connected in parallel to the first a-contact Til, and the auxiliary contact Ril, which is the a-contact of the electromagnetic contactor Ri, is connected in parallel to the second a-contact Ti2.

Then, after a set operating time has elapsed since the application of the operating voltage, the timer Ti operates the first and second a contacts Ti1.
Ti2 is closed, but even if the applied voltage is cut off, the contact signal is maintained for a short time tD.

Next, the auxiliary relay Ki is connected to the 1a contact Ti of the timer Ti.
1 is turned on, the timer Ti is self-maintained by the a contact Ki1, and the excitation of the timer Ti is cut off by the b contact Ki2.

Furthermore, even if the excitation voltage is cut off, this auxiliary relay Ki will remain active for a period of time t.
The K only contact signal is held.

Further, the electromagnetic contactor Ri is connected to the second a contact Ti of the timer Ti.
2 is turned ON, and is self-held by the auxiliary contact Ri1, and the input voltage applied to the welding machine side connector L is outputted to the welding jig side output terminal H by the main contact Ri2.

Furthermore, this electromagnetic contactor Ri maintains the contact signal for a time tR even if the excitation voltage is cut off, and maintains the contact signal for a time t'R (t'R≧tR) even when the excitation voltage drops to the short circuit voltage. The signal is preserved.

The delay time tD of the timer Ti mentioned above is a function added to the timer to ensure that the self-holding circuit of the auxiliary relay Ki and the electromagnetic contactor Ri works, and after the self-holding circuit works, the a contact of the timer Tie, Ti2 may be opened.

:Figure 4 shows the circuit elements of the control circuit Ci, that is, the timer T.
FIG. 2 is an operational characteristic diagram of auxiliary relay Ki and electromagnetic contactor Ri.

First, regarding the operation of timer Ti, change the excitation voltage as indicated by the arrow.
When the voltage is gradually increased as shown in (2), the timer Ti starts counting when the voltage reaches VT.

However, the voltage vT is the welding machine W when the welding machine W is under no load.
The voltage is between the output voltage of the welding machine W during arc welding, that is, the no-load voltage ■3, and the arc voltage ■2.

If the excitation voltage is maintained at vT here, the a contact of the timer Ti closes after the operating time ti of the timer Ti.

After the a contact of the timer Ti is closed, if the excitation voltage is cut off as shown by the arrow ■, the a contact of the timer opens after time tD.

Note that if the excitation voltage is cut off as shown by the arrow ■ after the timer Ti starts counting and before the time ti has elapsed, the timer T
i is reset and returns to the initial state, and the a contact remains in the OFF state without closing.

Next, the operation of the auxiliary relay Ki will be explained.

When the excitation voltage applied to the auxiliary relay Ki is gradually increased as shown by the arrow ■ in Figure 4, when the voltage reaches vK, the electromagnetic force that tries to close the a contact becomes the force of the spring against it. The contact closes after a time tM.

Note that the voltage vK is the arc voltage V2 and the welding machine output voltage when the welding rod is grounded, that is, the ground voltage V1.
It is between.

If the excitation voltage is cut off from the state of vK as shown by the arrow ■, the a contact of the auxiliary relay Ki will open after a delay time of 1 has elapsed.

The operation of the magnetic contactor Ri is similar to that of the auxiliary relay Ki.

When the excitation voltage applied to the electromagnetic contactor Ri is gradually increased as shown by the arrow ■, when the voltage reaches vR, the electromagnetic force that tries to close the A contact overcomes the force of the spring, and after a time tL the contact closes. closes.

However, voltage vR is arc voltage V2 and ground voltage v1
However, the voltage vK is not necessarily the same as the voltage vK.

If the excitation voltage is cut off from the state of vR as shown by the arrow ■, the a contact of the electromagnetic contactor Ri will open after the delay time tR has elapsed.

The operating characteristics of each element constituting the control circuit have been described individually above, but how the control circuit, which is a combination of the elements, actually operates will be described below.

The time chart of the control circuit shown in FIG.
1, ......, connect only an arbitrary control circuit to the welding machine among the n control circuits indicated by the symbol Cn,
This shows the operation when welding is actually performed.

In FIG. 5, when the output (3) of the welding machine is applied to the control circuit Ci, the timer Ti is immediately excited and starts timing.

After the set operating time ti has elapsed, the timer Ti
The contacts of are closed, and the auxiliary relay Ki and the electromagnetic contactor Ri are energized.

After time tM, the a contact of the auxiliary relay Ki closes and the auxiliary relay Ki is self-held, and the b contact opens to cut off the excitation of the timer Ti.

Here, since the timer Ti is of the delayed release type, the contact remains closed for a time t1) even after the excitation is cut off.

The contact of the electromagnetic contactor Ri closes after a time tL after being excited.

Here, the delay time tD of the timer Ti mentioned above is If so, the operation of the electromagnetic contactor Ri is performed reliably.

When the contact of the electromagnetic contactor Ri closes, the input terminal and output terminal of the control circuit Ci are connected, voltage is applied to m jigs connected to the output terminal side, and the welding rod with the processed tip is passed through the first welding rod. A short circuit occurs and a short circuit current flows.

Therefore, the current voltage of the control circuit decreases from the no-load voltage (3) to the short-circuit voltage V1.

Here, the excitation of the auxiliary relay Ki and the magnetic contactor Ri is O
The state shifts to the FF state, but since both are of the delayed release type, their contact states do not change immediately.

After the tip of the welding rod enters the short-circuit state, the welding rod normally enters the arc state after a while.

The duration time tA of the short circuit state is usually shorter than the delay time tK of the auxiliary relay Ki and the delay time tR of the magnetic contactor Ri, and therefore the contact states of the auxiliary relay Ki and the magnetic contactor Ri change during the time tA. There's nothing to do.

Therefore, the current is supplied and is not cut off until the tip of the welding rod changes from the short-circuited state to the arced state.

When the tip of the welding rod transitions to the arc state, the power supply voltage becomes v2
, and the auxiliary relay Ki and the electromagnetic contactor Ri are energized again.

The arc state continues for a time tw, during which time the control circuit C
All m welding rods connected to i are melted, and the power supply voltage rises to ■3.

Here, since the b contact of the auxiliary relay Ki remains open, the timer Ti does not operate again.

Welding is completed in this way, and if the output of the welding machine is cut off at this point, the contacts of the auxiliary relay Ki will be reset after a time tK, and the contacts of the electromagnetic contactor Ri will be opened after a time tH.

The time chart in FIG. 5 has shown the operation of the control device when the tip of the welding rod normally transitions from a short circuit state to an arc state (this is normal).

However, such a normal transition is not always guaranteed (though in rare cases, the transition to the arc state may not be successful and the short-circuit state may continue for a long time).

In such a case, there is a possibility that the welding machine will be burnt out due to the heat, and in order to avoid this, it is necessary to provide a means to prevent a long-term short circuit, and the control circuit of the present invention is equipped with this function. ing.

FIG. 6 is a time chart showing the operation of the control circuit when the short-circuit condition continues for a long time, that is, when ignition fails.

In FIG. 6, in the first half, the contact of the timer Ti closes after a time ti after the power supply voltage is applied, and the contact of the electromagnetic contactor Ri closes after a further time tL, a short-circuit current flows to the tip of the welding rod, and the power supply voltage increases. (2) The process from 3 to Vl is exactly the same as the case shown in FIG.

Then, when the power supply voltage drops to the short circuit voltage, the excitation of the auxiliary relay Ki and the electromagnetic contactor Ri is turned off.

Under normal conditions, this short-circuit state transitions to an arc state after a short time tA has elapsed as shown in Fig. 5, even though the auxiliary relay Ki and the electromagnetic contactor Ri are not energized during this time. , their contacts are kept energized.

However, when the short-circuit condition continues for a long time and time 1/2 has elapsed, the contact of the electromagnetic contactor Ri is released and becomes OFF, and the electric path connecting the input terminal and the output terminal of the control circuit Ci is cut off.

Therefore, the power supply voltage rises to the no-load voltage ■3.

Here, the time t'R is a value somewhat larger than the delay time tR of the electromagnetic contactor Ri.

As shown in FIG. 4, the delay time tB is the time from when the excitation is completely cut off until the contact becomes OFF state. In the welding rod short-circuit state, the excitation state of the electromagnetic contactor Ri is as follows. Although it is turned off, it is not completely cut off.

Therefore, the delay time t'R in such a case has a value somewhat larger than tR.

Also, the delay time tK of the auxiliary relay Ki is the electromagnetic contactor Ri
Since the delay time of the magnetic contactor Ri is longer than the delay time of
Even when it becomes FF, the b contact of the auxiliary relay Ki remains OFF and does not change, and even if the power supply voltage increases from ■ to ■3, the timer is not excited again.

Note that if the power supply voltage is turned off, Ki
contacts are reset.

From the above, it has become clear that when the arc welding rod fails to ignite and the short circuit continues for a long time, the short circuit prevention function Di provided in the control circuit Ci of the present invention works well.

However, long-term short circuits are not only a case of ignition failure;
It can also occur due to accidents such as cable damage.

Such a short circuit accident occurs downstream of the control circuit Ci, that is, in the electrical path connected to the output terminal of the control circuit Ci, during the period from time t to t' in FIG.

If a short circuit accident occurs during this period, time t'R
It is easily understood that if the short-circuit condition continues for a period of time, the contact point of the electromagnetic contactor Ri is released, and the situation is exactly the same as that after time 1' in FIG. 6.

Therefore, the control circuit Ci of the present invention is equipped with a short-circuit prevention function Di for dealing with short-circuit accidents.

The above has described how each control circuit Ci operates independently, but when multiple control circuits are connected to a welding machine, that is, when a system like the one shown in Figure 1 is configured, the individual control circuits The following describes how the control circuits interact and operate.

Figure 1 shows C1 of n control circuits from C1 to Cn.
, C2, and C3 are operation time charts.

Moreover, what is shown in FIG. 7 shows an example in which the parts connected to the control circuits C□ and C3 succeeded in firing, and the part connected to C2 failed in firing.

First, when the output of the welding machine is turned on and voltage V3 is applied to each control circuit C1 to C3, the timers T, , T of each control circuit are activated.
2 and T3 are simultaneously excited and start timing.

Here, each timer T1. The operating time of T2 and T3 is 1. , 12 and t3, with tl being the smallest value.

Therefore, first the contact of timer T1 closes and control circuit C
Welding starts from series 1.

What should be noted here is that the contact of the electromagnetic contactor R1 closes, the power supply voltage drops to ■, and the excitation of timer T2 is turned off.
The point is that it is necessary that the contacts of timer T2 do not close until the condition is reached.

That is, That is the point.

If these conditions are not met, the control circuit C
1 series and C2 series operate in parallel, and a situation occurs in which the short-circuit prevention function D1 or D2 of either the control circuit C1 or C2 is activated and the series is brought to an operation termination state.

Therefore, each timer T1. T2.・・・・・・・・・、
Tn operating time 11, 12.・・・・・・・・・,tn
As for that, you have to let it go.

Next, let us examine the point in time when welding of the control circuit C0 series is completed.

At this point, the power supply voltage increases from ■2 to ■3, and the timer T
Timer T2 and T3 are energized, but timer T1 is not energized because the b contact of 1 in the auxiliary relay is open and is in the OFF state.

In other words, once the timer has worked, it will not work again due to the memory function using the auxiliary relay.

Therefore, timer T2, which has the shortest operating time among the excited timers, operates, and welding of the series of control circuit C2 begins.

The control circuit C2 series shows an example in which ignition failed, and when ignition failed and the contact of electromagnetic contactor R2 opened and the power supply voltage rose to ■3, the auxiliary relay's B contact 2 It is in the open state, and therefore this series is also in the same state as when welding has been completed, and timer T3 is activated without operating timer T2 again and welding of the series of control circuit C3 is started.

In this way, it has become clear that the welding state is sequentially transferred to the series of control circuits C1, C2, and C3, but the same applies when there are n control circuits, so the explanation will be omitted.

Furthermore, when all control circuits are activated and the work is completed,
As long as the output of the welding machine is turned off, all control circuits automatically return to the initial state after time tK.

As described above, according to the automatic welding method using a coated arc welding rod of the present invention and its control device, a large number of coated arc welding rods connected to one welding machine are sequentially ignited, and long distances can be automatically and unattended. Furthermore, in the event of an ignition failure, short circuit, etc., that part can be skipped and welding can be continued on the next part.

[Brief explanation of drawings]

The drawings show an embodiment of the automatic welding method using a coated arc welding rod of the present invention and its control device, with FIG. 1 being an overall explanatory diagram of the automatic welding method, FIG. 2 being an external view of the control circuit, and FIG. is a wiring diagram of the control circuit, Fig. 4 is an explanatory diagram of the operation of the circuit elements, Fig. 5 is a time chart of the control circuit in a successful ignition example,
Figure 6 is a time chart of the control circuit in the case of ignition failure, Figure 7
The figure is a time chart of the entire system. W...Welding machine, Ci...Control circuit, A
i...Timer function, Bi...Circuit opening/closing function, Di...Short circuit prevention function, Ei...
・Memory function, 1-1.・・・・・・nm・・・、・・・
Welding jig, P...Welding rod, Ti...Delayed release timer, Ki...Delayed release auxiliary relay, Ri...Delayed release type electromagnetic contactor.

Claims (1)

[Claims] 1. In automatic welding using a coated arc welding rod, the no-load voltage and arc voltage of the welding power source are connected in the middle of a power cable connecting one welding machine and a plurality of welding jigs. a timer function that starts and resets the time at a voltage between 1 and 2; a circuit opening/closing function that closes the welding power supply circuit upon activation of the timer function; a short circuit prevention function that opens the circuit opening/closing function in the event of a short circuit accident; Inserting a control circuit having a memory function that stores the operation of the function and stopping the operation of the timer function, and setting the timer operation time of the timer function in each of the control circuits to different states in advance, Applying the output voltage of the welding machine to each of the control circuits, sequentially operating the control circuit that has a built-in timer function with a shorter operating time setting, and applying the welding machine output voltage to the welding jig and welding rod connected to the control circuit. let me,
An automatic welding method using a coated arc welding rod, characterized by automatically performing sequential arc welding. 2. In automatic welding using a coated arc welding rod, an input terminal connected to the welding machine and the welding jig are connected in the middle of a power cable connecting one welding machine and multiple welding jigs. The control circuits are connected to the input terminals respectively, and the control circuits are connected to the input terminals to control the output no-load voltage, arc voltage, and short-circuit voltage of the welding machine. A delayed release timer that starts and resets at a voltage between the arc voltage and the short-circuit voltage and can set an arbitrary operating time, and a delayed release timer that operates at a voltage between the arc voltage and the short-circuit voltage and whose delay time is set when voltage is applied to the welding rod. A delayed release type magnetic contactor which has a delay time longer than the time required for the arc to become stable after ignition and closes the main contact between the input terminal and the output terminal, and a voltage between the arc voltage and the short circuit voltage. and a delayed release type auxiliary relay that operates and has a delay time sufficiently longer than the delay time of the electromagnetic contactor, and the timer starts timing when a no-load voltage is applied to the input terminal of the control circuit, A self-holding circuit is added to the auxiliary relay so that the auxiliary relay and the electromagnetic contactor are turned ON and the main contacts are closed after a set operating time, and the timer is not energized again. The excitation of the timer is cut off, and further,
A short-circuit prevention function is provided which opens the main contact by releasing the electromagnetic contactor when an abnormal short-circuit phenomenon occurs that is longer than the delay time of the electromagnetic contactor, and stores that the auxiliary relay has been operated without being released. An automatic welding control device using a coated arc welding rod.