JPH0719669Y2 - Arc length control device - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to an arc length control device, and in particular, enables stable control of the arc length regardless of changes in arc current and other welding conditions during arc welding. Arc length control device.

[Conventional technology]

In the conventional device, as shown in FIG. 2, the voltage E input to the voltage input terminal 1 is applied to each of the lower limit comparator 2 and the upper limit comparator 3, and becomes a reference voltage for arc length control.
Compared to E _o . The voltage E _o can be arbitrarily set by the reference voltage setting volume 4.

A torch rising relay (Ry1) is connected to the output terminal of the lower limit comparator 2.
5, a torch lower limit relay (Ry2) 6 is connected to the output terminal of the upper limit comparator 3.

In the above configuration, the upper limit comparator 3 compares the set voltage (E _o + ΔV) with the arc voltage E, and E> (E _o −ΔV
When V) is satisfied, the relay 6 is operated to control the torch drive mechanism to lower the torch.

Further, the lower limit comparator 2 compares the set voltage (E _o −ΔV) with the arc voltage E, and when E <(E _o −ΔV) is satisfied, the relay 5 is operated to raise the torch. That is, the arc length can be kept constant by moving the torch up and down so that the arc voltage E falls within the range of the set voltage (E _o ± ΔV).

In MIG and MAG welding using consumable electrodes, since a constant voltage power supply is used, the arc current is controlled to be constant and the arc length is kept constant.
It is almost the same as TIG welding.

[Problems to be solved by the invention]

By the way, in the conventional example as described above, the welding condition is changed during welding, for example, when the arc current is changed during welding, the arc voltage is also changed, whereby the arc length is changed (when the arc current is increased, The arc voltage rises and E>
As (E _o + ΔV), the torch descends and the arc length shortens, which causes incomplete melting of the additive wire and causes welding defects. ).

Therefore, when changing the welding conditions, the arc length setting volume must be adjusted at the same time, which is a problem in that the operation becomes troublesome.

Further, conventionally, a constant arc length welding apparatus as described in Japanese Patent Publication No. 47-2164 has been proposed. This welding device detects the arc current in order to keep the arc length constant even if the arc current changes, and a current-voltage reference function generating circuit that cancels the change is provided on the input side of the comparator. The torch drive mechanism is controlled by the output signal of the vessel to control the arc length constant.

However, this welding apparatus requires a complicated current-voltage reference function generating circuit, which increases the cost of the apparatus.

Further, an arc welding method as described in Japanese Patent Publication No. 61-14914 has been proposed. In this method, a changeover switch is provided between the comparator and the torch drive mechanism, and the reference signal to the comparator is set by the arc voltage setting device while the torch drive mechanism is separated by this changeover switch. There is.

However, in this welding method, the position of the sliding terminal of the arc voltage setting device is set so that the reference signal is set to zero while watching the pointer position of the voltmeter provided on the output side of the comparator. It is necessary to make adjustments, which complicates the work.

Further, in such an external adoption method of the reference signal, it takes time to set the reference signal, and further, the setting accuracy is lowered and there is a problem in reliability.

The present invention has been made in view of the above-mentioned conventional circumstances, and an object of the present invention is to provide an arc length control device capable of controlling the arc length to a constant value regardless of changes in conditions during welding. Where it is.

[Means for solving problems]

In order to solve the above problems, the present invention relates to an arc length control device for maintaining a constant arc length by moving a torch up and down so that arc voltage or arc current falls within a set range. And welding condition change detection means for detecting completion of change, and storage means for storing arc voltage or arc current at the time of completion of change when detecting start and end of change of welding conditions by the welding condition change detection means, When the start of changing the welding condition is detected by the welding condition change detecting means, the stop of the lifting operation of the torch is started,
Elevation stop means for maintaining the stop of the ascending / descending operation of the torch until the welding condition change detecting means detects the completion of the welding condition change, and the welding condition change detecting means for maintaining the arc length before the condition change. When the completion of the change is detected, the storage means is provided with a control means for controlling the arc length with the arc voltage or the arc current at the time of the completion of the change of the welding condition as a reference value. is there.

[Action]

According to the above means, as the welding conditions are changed, the torch ascending / descending is stopped to maintain the arc length before the conditions are changed, and when the welding conditions are changed, the arc voltage at that time is set as a new reference value, and based on this reference value Since it becomes possible to perform the subsequent control, it is possible to configure an arc length control device that does not require readjustment of the arc length setting volume.

〔Example〕

 An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram illustrating an embodiment of the present invention.
Note that, in FIG. 1, the same parts as those in FIG. 2 have the same reference numerals, and a duplicated description will be omitted.

As the switches operated by the user, a torch raising switch 9 and a torch lowering switch 10 are provided, and the relay 5 and the relay 6 are connected in series, respectively, and are connected to the DC power supply 14. A condition modification request switch 11 and a welding start switch 12 are provided, and a condition change detection relay (Ry3) 7 and a timer relay (TM) 8 are connected in series to each other and connected to a DC power supply 14. The normally open contacts of the relays 5, 6 and 7 are connected in parallel, and the normally closed contact of the timer relay 8 is connected in parallel to the parallel circuit. The voltage input terminal 1 is connected to one end of this circuit, and the reference voltage storage device 13 for storing the arc voltage E at the time of completion of the welding condition change request is connected to the other end.

Further, the normally open contact of the timer relay 8 and the normally closed contact of the relay 7 are connected in series, and the lower limit comparator 2 and the torch raising relay 5 are connected.
It is inserted and connected between and. Further, another normally open contact of the timer relay 8 and another normally closed contact of the relay 7 are connected in series,
It is inserted and connected between the upper limit comparator 3 and the torch lowering relay 6.

The torch raising switch 9 and the torch lowering switch 10 are used when the torch needs to be raised or lowered during welding or not, and these switches are used to raise the torch 5, the torch lowering relay. 6 can be operated arbitrarily.

The condition change request switch 11 is a switch for changing a part or all of welding conditions during welding, and shifts the entire condition to the next step as the switch for increasing or decreasing the arc current and the progress of welding. It is linked to a switch. The condition change detection relay 7 (Ry3) detects whether the welding condition has been changed.

The welding start switch 12 is interlocked with the start switch of the welding device, and notifies the arc length control device that welding has started, an arc current has flowed, and control has entered the main sequence.

Next, the operation of the arc length control device having the above configuration will be described.

Once welding is started and control enters the main sequence,
By this sequence, the welding start switch 11 is automatically turned on, and the timer relay 8 starts operating. The timer relay 8 at the time of starting the operation does not operate the built-in contact group. When the time set by the timer relay 8 (time until the welding is stabilized) elapses, the relay 8 is turned on to close the normally open contact and open the normally closed contact. As a result, the supply of the arc voltage E to the reference voltage storage device 13 is cut off, and at the same time, the outputs of the lower limit comparator 2 and the upper limit comparator 3 are applied to the relays 5 and 6, respectively. As a result, the structure shown in FIG. 2 is formed and the arc length is controlled. At this time, E _o is output from the reference voltage storage device 13 as the reference voltage.

Next, a case where a request for changing the welding conditions is generated during welding will be described.

For example, when a change that increases the arc current occurs, the condition change request switch 11 is automatically turned on by the sequence, the condition change detection relay 7 is activated, and the change of the welding condition is detected. Opening the normally closed contact of the relay 7 turns off the relays 5 and 6, and the torch movement is forcibly stopped. At the same time, the normally open contact is closed, the arc voltage E of the voltage input terminal 1 is applied to the reference voltage storage device 13,
This is stored in the reference voltage storage device 13. As a result, the arc voltage E is rewritten to the new reference voltage E _o . During this time, the outputs of the comparators 2 and 3 have the normally closed contact of the relay 7 open, so that the torch ascends and descends and the arc length is not controlled.

When the welding condition setting is completed, the condition change request switch 11
Is turned off, the relay 7 is demagnetized, the normally open contact is opened, the normally closed contact is returned to closed, and the relays 5 and 6 are connected to the comparators 2 and 3. As a result, the arc length control is performed by the reference voltage E _o stored in the reference voltage storage device 13.

The arc length can be changed by operating the torch raising switch 9 or the torch lowering switch 10 to move the torch up and down. For example, when it is desired to increase the arc length, pressing the switch 9 causes the relay 5 to operate, and the torch rises regardless of the above control. At this time, the relay 5 is excited and the normally open contact is closed, so that the arc voltage E at that time is
Is stored in the reference voltage storage device 13, and the reference voltage is rewritten. When the torch raising switch 9 is turned off when the arc length reaches the desired length, the relay 5 is demagnetized and the application of the arc voltage E to the reference voltage storage device 13 is turned off. Therefore, the arc length is controlled by the new reference voltage E _o stored in the reference voltage storage device 13.

The above explanation has been made using TIG welding as an example.
The present invention can also be applied to G, MAG (GMA) welding.

Unlike TIG welding, GMA welding uses a constant voltage power source and the arc length largely depends on the arc current.
Therefore, the arc length control is performed not by the reference arc voltage but by storing the reference arc current.
The principle configuration of the device is the same as in FIG.

Further, in the above embodiment, the arc voltage is used as the reference value, but the arc current may be used as the reference value.

[Effect of device]

As described above, according to the present invention, since the arc voltage or current at the time of change is used as the reference value for changing the welding condition, the arc length can be changed even if the welding condition is changed. There is no. Furthermore, since there is no need to readjust the arc setting voltage, there is no trouble in use.

Further, unlike the conventionally proposed constant arc length welding apparatus, it is not necessary to provide a complicated current-voltage reference function generating circuit, so that the cost of the apparatus is not increased. Furthermore, unlike the welding method proposed in the past, the complicated work of adjusting the arc voltage setting device and setting the reference signal while looking at the pointer of the voltmeter is not required. Since the method is a content introduction method in which the reference is directly incorporated into the storage means by using the means, the conditions can be changed in a short time and the setting accuracy is high.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram showing a conventional arc length control device. 1 ... Voltage input terminal, 2 ... Lower limit comparator, 3 ... Upper limit comparator, 5 ... Torch up relay, 6 ... Torch down relay, 7 ... Condition change detection relay, 8 ... Timer relay,
9 ... Torch up switch, 10 ... Torch down switch, 11 ... Condition change request switch, 12 ... Welding start switch, 13 ... Reference voltage storage device, TM _o , Ry1 _o , Ry2 _o , Ry3
_o …… Normally open contact, TM _c , Ry3 _c …… Normally closed contact.

Claims (1)

[Scope of utility model registration request] Claim: What is claimed is: 1. An arc length control device for maintaining a constant arc length by raising and lowering a torch so that an arc voltage or an arc current falls within a set range. Welding detecting start and end of change of welding conditions during arc welding. Condition change detection means (7), and a storage means (13) for storing the arc voltage or arc current at the time of completion of the change when the welding condition change detection means (7) detects the start and end of the change of the welding conditions. When the welding condition change detecting means (7) detects the start of welding condition change, the torch raising / lowering operation is stopped, and the welding condition change detecting means (7) until the welding condition change completion is detected by the torch. Lifting stop means (5, 6, 7) for maintaining the arc length before the condition change while maintaining the stop of the ascending / descending movement of the welding condition, and the welding condition change detecting means for changing the welding condition. Upon detection of the completion, control means for controlling the arc length as a reference value the arc voltage or arc current of the newly changed the stored the welding conditions at the time of completion in the storage means (1,2,3,5,6,1
3) An arc length control device characterized by having and.