JPS6114080A - Consumable electrode type arc welding device - Google Patents

Abstract

PURPOSE:To obtain a titled device for raising an alarm and also preventing an accident of the time when starting an arc, by setting a wire to a feed light contact state, generating the arc by a large current and feeding the wire in reverse, and thereafter, executing a normal feed arc welding, and lifting and stopping the wire in the event of an abnormal contact. CONSTITUTION:When welding start switch PB1 is turned on, a contact CR1 is energized and a wire 2 descends by a welding power source 1 and a small current of a motor control circuit 8. By a contact of an object to be welded of a wire, a current detector is operated and by a relay CR4, a wire 1 ascends a little and becomes a light contact state. By a timer TD3a, the relay CR4 and a setting device VR2, the wire 1 ascends suddenly, also an arc is generated, and thereafter, welding is executed by a normal feed of the setting device VR2. When a contact WCR7 is not operated, the wire 1 ascends suddently and stops by timers TD1, TD1a and a relay CR3, and an alarm PL is raised. Accordingly, an abnormal accident of the time when starting an arc is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to improvements in arc welding equipment using consumable electrode wires.

Conventional technology The method of starting the arc in automatic arc welding using a consumable electrode wire is to start feeding at a relatively low speed while applying high welding power to the electrode wire, and to make contact between the electrode wire and the object to be welded. The wire slow-down method uses a large short-circuit current that flows to melt and scatter the tip of the electrode wire and transfer it to an arc, and the wire slow-down method uses a high-frequency high voltage in addition to the welding power output between the electrode wire and the workpiece. A method is used in which the arc is started by applying a voltage to break the insulation in the gap between the two. However, the former has a poor arc start success rate (particularly when using thick electrode wires such as in submerged arc welding, or when using wires such as aluminum with low resistivity and less resistance heat generation due to short circuit current) was extremely difficult to generate.

Furthermore, when using the latter method, not only is it necessary to strengthen the dielectric strength of the equipment, but also malfunction of the equipment itself due to the incorporation of high frequency noise and induction disturbances to peripheral equipment cannot be avoided, resulting in many practical problems. Therefore, as a countermeasure to these problems, the electrode wire is fed until it comes into contact with the workpiece, and then the electrode is fed backwards with the short-circuit current flowing, thereby forcibly separating the two. A so-called IJ I-lacto start method has been proposed, in which the electrode wire is fed forward after a minute arc has grown, and normal arc welding is performed.When this method is used, the success rate of arc start is relatively high.Especially A method that supplies power from a power source that supplies a small short-circuit current until it first detects a short circuit, and detects contact between the electrode and the workpiece based on the presence or absence of output current from this power source, Since no short-circuit current flows, there is no risk of the electrode welding to the workpiece, and relatively good results can be obtained.However, when using this method, the tip of the electrode wire or the workpiece There was no solution provided for the case where there was some kind of insulator on the surface of the electrode wire and no contact was detected electrically even though the two were in mechanical contact. If there is an insulator such as slag, mill scale, or rust on the surface of the wire or the workpiece, electrical contact will not be detected even if the two come into mechanical contact.This can cause arcing and melting of the wire. If neither of these occurs, either the electrode wire bends or the feeding mechanism slips due to this continued feeding of the electrode wire. The welding torch receives a reaction force from the wire feeding force, causing the entire welding device to fall, break, or break.Moreover, in carbon dioxide arc welding and sub-arge arc welding, the tip of the electrode wire is Slag and oxides are always attached at the end of welding, and there are also insulators such as slag, spatter, and sprinkled flux on the surface of the welded object, so the insulation between the two is always maintained as described above. For this reason, it is not possible to omit inspection of the tip of the electrode wire and the surface of the workpiece prior to the start of welding, and complete unmanned operation has not been possible.

Purpose of the invention 5. Yo, yowagae□b and two a, 6゜ 1
”, even if an insulation condition occurs between the electrode and the proboscis to be welded when feeding the electrode wire, the operation can be safely stopped without causing any trouble to the welding equipment, allowing unattended operation. This prevents the welding equipment from being destroyed even if the welding process is carried out.

SUMMARY OF THE INVENTION The present invention includes a wire touch detection circuit that detects electrical contact between an electrode wire and a workpiece, and determines that there is an abnormality when wire touch is not detected even after the wire feeding amount reaches a predetermined amount. The above-mentioned problems are solved by providing means.

Embodiment FIG. 1 is a connection diagram showing an embodiment of the apparatus of the present invention. FIG. ) is a welding power supply connection diagram. In the figure, 1 is a welding power source, and its output is determined by output setting devices VR4 and VR5. 2 is a consumable electrode wire (hereinafter simply referred to as wire), and 3 is a welding power source. The object to be welded, 4 is a wire feeding electric motor, 5
is a feeding roll driven by a wire feeding electric motor 4.

6 is a voltage detector, which has a contact signal AVR that closes when the voltage between the wire 2 and the workpiece 3 exceeds a certain level; 7 is a current detector, which detects when even a small amount of current flows into the welding circuit. It has a contact signal WCR that operates when flowing. Reference numeral 8 denotes a control circuit for the wire feeding electric motor 4, which controls the electric motor 4 so that the wire 2 reaches the rotational speed determined by the setting devices VR1 to VR3, and when a command signal is input to the F terminal. The speed and direction of rotation are controlled so that the wire is rotated in the direction in which the wire is fed (forward feed direction), and in the direction in which the wire is pulled up (reverse feed direction) when the wire is input to the terminal. .

CR1 to CR5 are relays and CRla to CR
5a is a normally open contact of each of these relays.

CIJb to CR5b indicate normally closed contacts. TDI to TD3 are delay operation type timers, and TDla and T
D3a is the normally open contact of timers TD1 and TD3, TD
, 2b indicates a normally closed connection of timer TD2. FBI is a push-button switch for starting welding, PB2 is a push-button switch for stopping welding, and PB3 is a push-button switch for resetting and turning off poor contact detection. PL is an indicator light that lights up when a contact failure is detected, and there is a flashing display for warning,
It can be changed to a buzzer, etc. 9 is AC power supply, E
is a DC power supply.

The output setting device VR5 is used to set the output voltage or output current so that a small current that does not melt the wire 2 flows when the wire 2 comes into contact with the workpiece 3, depending on the characteristics of the welding power source 1. The setting target is selected. The output setting device VR4 is used to set the output during welding, and as an output setting device for welding, a setting device for reducing the output at the end of welding is also required, but this does not meet the gist of the present invention. There is no direct relationship, so I'm just trying to simplify the explanation.
D is omitted. Further, the setting device VR1 is used to set the wire feeding speed when the wire 2 is fed toward the workpiece 3 at a low speed at the start of welding, and the setting device VR2 is used to set the wire feeding speed during welding. This is a setting device for setting.

The setting device VR3 is a setting device for applying a weak driving force to the electric motor 4 that does not substantially reverse the wire 2,
Unlike the other two setting devices VR1 and V'R2, this setting device sets the torque generated by the electric motor 4. In addition, after this weak reverse operation, the setting device VR2 increases the output of the welding power source to a high output, and at the same time, the speed setting device is used to substantially reverse feed the wire, and when a contact failure is detected, the setting device VR2 reverses and pulls up the wire. It is also used as a speed setting device.

In the embodiment shown in the figure, the welding start push button switch P
Pressing B1 energizes relay CR1.

The normally open contact CR1a is closed by the excitation of the relay CRI, and the output setter VR5 and the setter ■R1 are connected to the welding power source 1 and the motor control circuit 8, respectively. As a result, an output that allows a small short-circuit current to flow between the wire 2 and the workpiece 3 is supplied. Further, the electric motor 4 rotates at a relatively low speed determined by the setting device VR1, and the wire 2 is slowly fed toward the workpiece 3. When the wire 2 comes into contact with the workpiece 3), a short-circuit current will flow if there is no insulator, and this short-circuit current will be transmitted to the current detector 7. is detected and the output contact WCR is activated. Relay CR2 is excited by the operation of this contact WCR, and this relay CR2
The setting device ■R1 is disconnected by the normally closed contact ci2b,
The setting device VR3 is connected to a terminal of the motor control circuit 8 by a normally open contact CR2a. For this reason, the electric motor 4 stops normal rotation, and rotates in the reverse direction in accordance with the setting value of the setting device VR3 in a direction to pull up the wire 2. However, since the setting value of the setting device VR3 is set to a value that provides a weak driving force as described above, the electric motor 1 motor 4 is affected by the backlash of the speed reduction mechanism connected to it and the wire 2 that is not correct at the beginning. It reverses only during a very light load state until the force pressed against the workpiece 3 due to inertia during feeding is released,
When the wire is actually fed back, a large driving force is required, so the electric motor 4 does not rotate any further, and the wire is not pulled up but remains in very light contact with the workpiece. . On the other hand, normally open contact CR2 of relay CR2
a Hammer f: Since the timer TD3 is also excited, the timer TD3 also starts timing at the same time as the reverse rotation command for the electric motor 4 is issued. When contact TD3a closes due to the expiration of timer TD3, relays C and R4 are energized, and contact CR4 of relay CR'4 is energized.
a and CR4b change the output setting device from VR5 to VR4.
At the same time, the setting device of the motor control circuit 8 is also switched to V.
Switched from R3 to VR2.

As a result, the output of the welding power source 1 becomes a high output necessary for welding, and the feeding speed of the wire 2 also becomes a high speed determined by the setting device VR2, so that the number can be increased rapidly. This reverse feeding breaks the contact between the wire 2 and the workpiece 3, and an arc is generated by the high output of the welding power source 1 being supplied at this time. At this time, the ear 2 and the workpiece 3
Due to the weak reverse drive at the tip, the contact pressure between the two is almost zero, and the backlash of the feeding mechanism is also eliminated, so there is an extremely long delay in the wire pulling operation when the power supply is switched. The tip of the wire 2 easily melts and becomes an arc. If reverse feeding continues in this state, the arc will grow, and if the arc voltage at this time becomes higher than the set voltage of the voltage detector 6, the contact AV
R closes. As a result, relay CR5 is energized and its contacts Q' CR5a, CR5b.

The input of the motor control circuit 8 is switched from k to F. As a result, the direction of rotation of the electric motor 4 is reversed, and the direction of rotation of the electric motor 4 is reversed.
is fed forward at a speed determined by setting device VR2, and normal welding is started.

The apparatus of the embodiment shown in FIG. 1 operates as described above under normal conditions, but if the wire 2 is
If the wire and the workpiece 3 are insulated for some reason, a short circuit current cannot flow even if the wire mechanically contacts the workpiece 3, so the contact WCR of the current detector 7 will not operate. become. Therefore, the wire continues to be fed, but the timer TD1, which is energized at the same time as the closing of the welding start pushbutton switch, expires, causing the contact TDl to end.
When a is closed, relay CR3 is energized, and relay CR3 is self-held by its own normally open contact CR3a. At the same time, the F of the motor control circuit is activated by contact CR3b.
The input signal to the terminal is cut off and the motor 4 stops forward feeding the wire.

A warning of wire contact failure is displayed by an indicator light PL connected in parallel with relay CR3. Furthermore, the relay contact CR is connected to the motor control circuit 8 until the end of the time limit of the timer TD2.
An output of 2 is supplied to the setting device (2) through the terminal 3a, and the motor 4 rotates in reverse at high speed to pull up the wire 2. Once a wire contact failure is detected, relay CR3 is self-held, so no other operation can be performed until reset push/button switch PB3 is pressed. Therefore, after inspecting and correcting the wire tip and the surface condition of the workpiece, the operator presses the reset pushbutton switch PB3, and then presses the welding start pushbutton switch PB1 again to restart. As can be easily seen from the above operation, the time limit of timer 1 is set to be slightly longer than the time from the start of wire feeding to contact (usually about 0.3 to 33 seconds), and timer TD2
The time limit is the time required to return the wire in contact to its original position (usually about 0.1 to 1 second)
In addition, the timer TD3 may be set to 0.5 seconds to several seconds as long as it is longer than the time required to eliminate the backlash of the feeding mechanism and does not need to be exact. These timers are used to obtain the required amount of wire feeding or the amount of drive of the wire feeding mechanism, and each setting requires changing the time limit depending on the corresponding wire feeding speed. Even more accurate control can be achieved by configuring the timer to obtain the actual wire feeding amount by multiplying the rotation speed or feeding speed of the wire feeding mechanism by the feeding time and compare it with a preset value. becomes possible.

In the embodiment shown in FIG. 1, a timer TD2 was provided to automatically pull up the wire for a certain period of time when a wire contact failure was detected.
When a wire contact failure is not provided, the wire feeding mechanism immediately stops and maintains the state at the time of detection. Therefore, when the cause of wire contact failure can be easily determined and the welded part can be easily seen by the operator, it may be better not to perform automatic lifting except for timer TD2. In this case, the operator may manually reverse the wire as appropriate using a push button switch (not shown). Also wire feeding.

The timing of reverse feed, speed change, output switching of the welding power source, etc. is arbitrary, and processes such as stopping once and confirming restart command or automatic restart after stopping may be added as appropriate between each operation. Further, in conjunction with each of these operations, other operations necessary for welding, such as releasing shielding gas, spreading flux, and moving the welding torch, may be performed.

Furthermore, in the embodiment shown in Fig. 1, the arc starting operation is immediately interrupted when a wire contact failure is detected, but the insulation state between the wire and the workpiece is destroyed by a relatively slight impact. This is often due to the insulating material used. Therefore, instead of immediately interrupting the arc start operation when a wire-to-wire contact failure is detected, if you pull up the wire and then restart the arc start operation from the beginning, the insulation state will be resolved by the shock of the wire contact again. There is a possibility that a good arc start will be performed. A second aspect of the present invention proposes an apparatus provided with a circuit that repeatedly performs an arc start operation when a wire contact failure is detected. FIG. 2 shows a connection diagram of this embodiment. The device shown in the same figure is the embodiment shown in FIG.
R5, and also relay CR3 and timer T, D2
In addition to removing the self-holding circuit, the excitation of timer TD1 is cut off by the normally closed contact of timer TD2, so that the arc start operation is performed again from the beginning after the wire reverse feed time after detecting a wire contact failure. It is equipped with a repeating circuit.

Among the operations of the embodiment shown in the same figure, the operations when the wire contact is performed normally are the same as those of the embodiment shown in FIG. 0 Push button switch PB1 is pressed, relay CRI is energized, and wire 2 is connected to setting device ■R.
When the welding object 3 is fed at the low speed determined by 1, if the current detector 7' still does not detect any current and the contact WCR is not operating even when the timer TD1 expires. Relay CR3 and timer TD2 are energized due to poor wire contact. As a result, the input of the control circuit 8 is switched from the F terminal to the R terminal, and the setting device is also switched from ■R1 to VR2, and the wire 2 is connected to the setting device V.
It is pulled up at a speed determined by R2. When the normally closed contact TD2b opens due to the end of the time limit of timer TD2, timer TD
1 is de-energized, its normally open contact TDla is immediately opened, and relay CR3 and timer TD2 are de-energized. Therefore, the normally closed contact of the timer TD2 returns to its original state, and the timer TD1 is energized again, returning to the initial state in which the pushbutton switch PB1 was pressed. At this time, due to the return of the cutter CR3, the input of the control circuit 8 is once again supplied with the output of the setting device R1 to the F terminal, resulting in low-speed forward feeding. If the contact WCR of the current detector 8 does not operate within the time limit of the timer TD1 due to this normal feeding again, the relay CR3 and the timer TD2 are energized again and the feeding is repeated to pull up the wire 2 and resend it. At this time, each time relay CR3 is energized, preset counter CU1 counts through contact CR3a, and when this counted value matches the preset number, relay CR6 connected to the output terminal
is energized to de-energize relay C'R1 and interrupt subsequent operations.

The embodiment shown in Figure 2 operates as described above, so even if poor wire contact is detected, the wire is automatically pulled up and the arc start operation is repeated a predetermined number of times, thereby preventing slag from adhering to the tip of the wire. If the insulation condition is relatively weak, such as when the welding is done, arc starting will be performed without interrupting welding. In addition, if this insulation state is based on a strong insulator, it will stop after a predetermined number of trials, so it can prevent excessive (recurrence) and deform the tip of the wire or cause the wire feeding mechanism to overshoot. There is no risk of overload.

In each of the above embodiments, it is more effective if the wire is slightly swung parallel to the surface of the workpiece at the time of contact detection when the wire is fed. In particular, when the present invention is applied to an arc welding robot using the teaching playback method, the moving path of the welding torch can be arbitrarily taught, and an optimal swing trajectory can be drawn, so that the effects of the present invention can be more effectively demonstrated. It is something.

Further, the device of the present invention is not limited to the one constructed by a contact relay as shown in the drawings, but can also be constructed by a logic circuit using a semiconductor integrated circuit or the like.

Effects of the Invention As described above, the present invention has the following features: 1. In a consumable electrode type arc welding device that uses a retract start method in which the wire is once brought into contact with the workpiece and then forcibly pulled up to generate an arc, a predetermined amount of wire is We have installed a judgment circuit that determines that there is a poor contact when no contact is detected despite feeding, so unlike conventional equipment, there is no insulation such as slag, rust, or flux on the tip of the wire or on the surface of the workpiece. Even when an object is present, there is no need to continue feeding the wire as part of the contact detection process, making it possible to prevent wire bending, overturning or damage of the welding equipment, and improve the welding area. This enables welding to be carried out safely in narrow spaces where it is difficult to visually recognize the welding process, and completely unmanned operation is possible because accidents at arc start can be prevented.

[Brief explanation of the drawing]

FIGS. 1(a) and 1(b) are connection diagrams showing an embodiment of the apparatus of the present invention, and FIGS. 2(a) and 2(b) are connection diagrams showing another embodiment of the present invention. 1... Welding power source 2... Wire, 3... Work to be welded 4... Electric motor 6... Voltage detector 7
...Current detector 8...Motor control circuit CUl...
・Preset Counter Representative Patent Attorney Nakai
Hiroshi Procedural Amendment Self-Restraint August 3, 1980 1. Indication of the Case 1982 Patent Application No. 136090 @ 2. Name of the Invention Consumable Electrode Arc Welding Device 3. Person Making the Amendment Relationship with the Case Patent Applicant November 2-1, Tayo, Yodoyo-ku, Osaka (026) Osaka Transformer Co., Ltd. 4, Agent

Claims (1)

[Scope of Claims] 1. A wire touch detection circuit that detects electrical contact between a consumable electrode wire and a workpiece, a means for detecting a feed amount of the consumable electrode wire, and a wire touch detection circuit that detects electrical contact between a consumable electrode wire and a workpiece; a determination circuit that determines that there is a wire contact failure when the wire touch detection circuit does not detect contact between the electrode wire and the workpiece even when the wire feeding amount detected by the detection means reaches a predetermined amount; Consumable electrode type arc welding equipment. 2. The wire feeding amount detection means determines the feeding length from the start of wire feeding by the wire feeding time, the number of revolutions of the wire feeding mechanism, or the product of the wire feeding speed and the feeding time. The consumable electrode type arc welding apparatus according to claim 1, wherein the detecting means is based on: 3. The wire touch detection circuit is a circuit that outputs a wire reverse feed command signal to temporarily pull up the consumable electrode wire and generate an arc after detecting electrical contact between the consumable electrode wire and the workpiece. A consumable electrode type arc welding apparatus according to claim 1. 4. The wire touch detection circuit supplies power to flow a small short-circuit current that does not melt the consumable electrode wire between the consumable electrode wire and the workpiece by adjusting the output of the welding power source. 2. The consumable electrode type arc welding machine according to claim 1, wherein the circuit is a circuit for detecting contact between the consumable electrode wire and the object to be welded by the flow of a short circuit current. 5. The wire reverse feed command signal includes a first command signal that causes the wire feeding mechanism to perform a reverse feed operation to a degree that does not substantially reverse the consumable electrode wire, and an end of the first command signal. and a second command signal for substantially reversing the consumable electrode wire.
The consumable electrode type arc welding device described in 2. 6. The electric power supplied between the consumable electrode wire and the object to be welded is electric power that causes a small short-circuit current to flow so as not to melt the consumable electrode wire until the second command signal is supplied. The consumable electrode type arc welding apparatus according to claim 5, wherein after the second command signal is supplied, the electric power is switched to a value suitable for arc welding. 7. A wire touch detection circuit that detects electrical contact between the consumable electrode wire and the object to be welded, a feeding amount detecting means for the consumable electrode wire, and detection by the feeding amount detecting means at the time of starting welding. a determination circuit that determines that there is poor wire contact when the wire touch detection circuit does not detect contact between the electrode wire and the workpiece even when the wire feeding amount reaches a predetermined amount; A consumable electrode type arc welding device comprising a repeating circuit which reversely feeds the consumable electrode wire by a predetermined amount according to the output and restarts the consumable electrode wire after the reverse feed. 8. The repeating circuit is a circuit that stops the arc start operation if a poor wire contact is still detected even after repeating the arc start operation a predetermined number of times. Consumable electrode type arc welding equipment. 9. The wire touch detection circuit is a circuit that outputs a wire reverse feed command signal to temporarily pull up the consumable electrode wire and generate an arc after detecting electrical contact between the consumable electrode wire and the workpiece. A consumable electrode type arc welding apparatus according to claim 7 or 8. 10. The wire tatch detection circuit supplies power to flow a small short-circuit current that does not melt the consumable electrode wire between the consumable electrode wire and the workpiece by adjusting the output of the welding power source, 9. The consumable electrode type arc welding machine according to claim 7, wherein the circuit is a circuit that detects contact between the consumable electrode wire and the workpiece by flowing a short circuit current. 11. The wire reverse feeding command signal includes a first command signal that causes the wire feeding mechanism to perform a reverse feeding operation to the extent that the consumable electrode wire is not substantially reversed, and an end of the first command signal. and a second command signal for substantially reversing the consumable electrode wire. 12. The electric power supplied between the consumable electrode wire and the object to be welded is electric power that causes a small short-circuit current to flow so as not to melt the consumable electrode wire until the second command signal is supplied. 12. The consumable electrode type arc welding apparatus according to claim 11, wherein after the second command signal is supplied, the power is switched to a value suitable for arc welding.