JP2000218367A - Arc welding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an arc welding machine which can make quality of a welding completion part excellent in repetitive welding, without increasing the number of buttons of an operation switch. SOLUTION: This machine is equipped with a monitoring circuit 20 for monitoring close signals of an operation switch 1. When a repetitive welding is selected by a changing switch 3, a time interval from the closure of the operation switch 1 to the next closure is measured by the monitoring circuit 20. For example, when the time interval for closing the operation switch 1, is within 0.5 seconds, welding is completed. By providing a switch function to the time interval of closing the operation switch 1, control items can be increased without increasing the button number of the operation switch. In this case, the current is gradually reduced from the main welding current to be transferred to a crater current, and an after-flow time is provided, whereby quality of the welding completion part becomes excellent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an arc welding machine in which a welding current value is switched by an open / close signal of an operation switch.

[0002]

2. Description of the Related Art An arc welding machine is an apparatus used for TIG arc welding and the like. Such an arc welding machine will be described with reference to FIG. FIG. 5 is a control circuit configuration diagram of a conventional arc welding machine capable of performing TIG arc welding and manual welding. Reference numeral 1 denotes an operation switch, which is arranged on a torch (not shown) and includes an output control circuit 2 composed of a microcomputer or the like.
It is connected to the. A changeover switch 3 is connected to the output control circuit 2. The changeover switch 3 has contacts a, b, c
By switching the contacts a to c, a welding sequence described later can be selected. 4 is an up slope period Tus setting device, 5 is a down slope period Tds setting device, and 6 is an afterflow period Taf setting device, which are connected to the output control circuit 2 respectively. 7 is a start current value Is setting device, 8 is a main current value Im setting device, 9 is a crater current value Ic setting device, which are connected to the output control circuit 2 respectively. Note that the start current period Ts in which the start current value Is flows is divided into two cases: a case where a fixed value is set in advance in the output control circuit 2 and a case where the operation is continued while the operation switch is closed as described later. There are types. 1
Reference numeral 0 denotes a power supply control circuit which outputs a welding current specified by the output control circuit 2. Reference numeral 11 denotes a solenoid valve for shielding gas.

The reason why the welding sequence is set by the changeover switch 3 is as follows. That is, when the operation switch 1 is arranged on the torch, the operator operates without looking at the switch button. Therefore, in order to prevent an erroneous operation, the number of switch buttons is reduced to one, and a function of holding a close signal (hereinafter, referred to as self-holding) can be selected.

[0004] In the case shown in the figure, the output control circuit 2 executes the following welding sequence specified by the changeover switch 3 based on the open / close signal from the operation switch 1. That is,
When the contact a is selected, a welding sequence without self-holding and without self-holding is executed. When the contact b is selected, a welding sequence of one-time welding described later with self-holding is executed. When the contact c is selected,
The welding sequence of the repetitive welding described later with self-holding is executed.

Next, each of the conventional welding sequences will be described. 6A and 6B are diagrams showing an opening / closing signal, a welding current value, and an opening / closing operation of a solenoid valve by an operation switch in each conventional welding sequence. FIG.
(B) shows the case of single welding, and (c) shows the case of selecting repetitive welding. Tp in the figure is the preflow period, T
m is the main welding current period, Tc is the crater current period, Taf
Represents an afterflow period. In the illustrated case, the up slope period Tus and the down slope period Tds are set to 0.

In the case of (a), the operation switch 1 (S
The solenoid valve 11 is opened by the closing signal of W) to start the preflow period Tp, and the shielding gas is supplied to the torch (not shown). After the elapse of the preflow period Tp, the process proceeds to the main welding current period Tm, and a welding current having a current value of Im (hereinafter, referred to as a welding current Im; the same applies to other current values). When the start current period Ts elapses, the process proceeds to the main welding current period Tm, where the welding current Im
Is supplied to the weld. When the operation switch 1 is opened when the desired welding is completed, the supply of the welding current Im is stopped, and the after-flow period Taf is started. Afterflow period T set by afterflow period Taf setting device 6
When af elapses, the solenoid valve 11 closes, and the welding operation ends. The welding sequence without self-holding is adopted when tacking work or when the welding length is short.

In the case (b), when the operation switch 1 is closed, the preflow period Tp starts, and the preflow period Tp
When p elapses, the process proceeds to the start current period Ts, and the start current Is is supplied to the welding portion. When the operation switch 1 is opened, the start current period Ts ends, the process moves to the main welding current period Tm, and the welding current Im is supplied to the welding portion. 1
In the case of round welding, since the self-holding is performed, the operation switch 1 may be kept open during the main welding current period Tm. When the operation switch 1 is closed when the desired welding is completed, the operation proceeds to the crater current period Tc, and the welding current Ic is supplied while the operation switch 1 is closed. Then, by opening the operation switch 1, the afterflow period Taf is started. When the afterflow period Taf elapses, the solenoid valve 1
1 is closed and the welding operation is completed. The welding sequence of single welding is employed when the welding length is long or when craters are prevented from occurring.

[0008] In the case of (c), the operation is the same as that of the above (b) until the start of the first crater current period Tc. However, when the operation switch 1 is opened during the crater current period Tc, the main welding current period Tm is restarted. Transition. Hereinafter, according to the opening and closing of the operation switch 3, the main welding current period Tm and the crater current period Tc
repeat. When the welding is to be terminated, the torch is quickly pulled up to forcibly extinguish the arc. Then, the output control circuit 2 turns off the power supply control circuit 10 and closes the solenoid valve 11. The welding sequence of the repetitive welding is adopted when the thin plates and the welded portions are arranged at intervals.

In some cases, the start current value Is is set to be the same as the main welding current value Im. In addition, the start current period Ts is a short time at the start of welding and can be ignored compared to the main welding current period Tm. Therefore, the start current period Ts can be considered to be substantially included in the main welding current period Tm.

FIG. 7 is a diagram showing an example in which the welding current value is adjusted according to the welding period, and shows a case where welding is performed once by setting values other than 0 for the up slope period Tus and the down slope time Tds. ing. As shown in the drawing, when an up slope period Tus is provided in the main welding current period Tm, the main welding current Im is changed from the start current Is to the up slope period T
The period shifts to the main welding current Im in the period set by the us setting device 4. Further, if a down slope period Tds is provided in the crater current period Tc, the main welding current Im becomes the crater current I d during the period set by the down slope period Tds setting device 5.
Move to c.

In addition to the above, arc spot welding and manual welding can be performed, but the description is omitted because it is not related to the present invention.

[0012]

In the above prior art, when the repetitive welding is selected, the welding is terminated by rapidly pulling up the torch, so that not only a recess can be formed at the welding end, but also the gas at the welding end can be reduced. Insufficient shielding. For this reason, not only defects such as cracks occurred at the weld end portion, but also the appearance was reduced.

An object of the present invention is to solve the above-mentioned problems in the prior art, and to provide an arc welding machine capable of improving the quality of a welding end portion in repeated welding without increasing the number of operation switches. To be.

[0014]

In order to achieve the above-mentioned object, according to the present invention, a first welding current and a second welding current are set in advance, and a first closing of an operation switch is performed. The first welding current is supplied with a period from the signal to the second closing signal as a first period, and the period from the second closing signal to the next opening signal is set as a second period. Arc welding for supplying welding current No. 2 and moving to the first period again according to the open signal, and thereafter performing control so as to alternately switch the first period and the second period according to an open / close signal of the operation switch. The machine is provided with a monitoring circuit for monitoring a time interval of the closing signal, and when the closing signal is repeated within a predetermined time, the welding is controlled to be terminated.

The invention according to claim 2 is characterized in that, in claim 1, the predetermined time is 0.5 second.

The invention of claim 3 is characterized in that in claim 1 or claim 2, the welding current is gradually reduced at the end of welding.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. FIG. 1 is a control circuit configuration diagram of an arc welding machine according to the present invention. Components having the same functions or the same functions as those in FIG. In the figure, 2
Reference numeral 0 denotes a monitoring circuit, and an operation switch 1 and an output control circuit 2
It is connected to the.

Next, the operation of this embodiment will be described. FIG. 2 is a flowchart showing a control procedure in the present embodiment, FIG. 3 is a flowchart showing an operation of the monitoring circuit 20,
FIG. 4 is a diagram showing the relationship between the switching signal of the operation switch and the welding current.

First, the overall operation will be described with reference to FIG. When the operation switch is closed, the output control circuit 2 confirms whether or not there is self-holding (step S100 in FIG. 2). In the case of, step S12
0 processing is performed. In step S120, it is confirmed whether or not the welding is performed once. If the welding is performed once, the welding sequence control of the welding is performed in step S130.
Step 140 is performed. In step S140, the monitoring circuit 20 is turned on to enter a welding end condition loop (step S15).
0), until the signal from the monitoring circuit 20 is received, the welding is repeated in the same manner as in the related art (step S160). Monitoring circuit 20
(Step S170, at the end of the period t in FIG. 4), the following welding end processing is performed. That is, the welding current value is reduced by a predetermined ratio from the main welding current Im (step S200), and when the welding current value falls to the same value as the crater current Ic (step S210),
The power supply control circuit 10 is turned off (procedure S220), and after a predetermined time Taf elapses (procedure S230),
The solenoid valve 11 is closed (procedure S240).

Next, the operation of the monitoring circuit 20 will be described. The monitoring circuit 20 turned on in step S140 resets the internal timer (step S300) and waits for a closing signal of the operation switch 1 (step S310). Upon receiving the closing signal of the operation switch 1, measurement of the time t is started (step S32).
0), and waits for the next closing signal (procedure S330). When the next closing signal is received, the measured time t until then is compared with 0.5 seconds (step S340), and if the measured time t is 0.5 seconds or less, a signal is output to the output control circuit 2. (Step S3
50) When the processing is completed and it is longer than 0.5 seconds, the procedure 3 is performed.
00 is performed.

In the case of the above-mentioned embodiment, since the welding end portion can be reliably gas shielded, the appearance of the welding end portion becomes beautiful. Further, since the welding current at the end of welding is gradually reduced from the main welding current Im to the crater current Ic, the crater at the end of welding can be reduced, and the occurrence of cracks and the like can be reduced.

In the above description, the welding current is equal to the crater current I.
The current supply was stopped when it became c,
The crater current Ic may be maintained for a predetermined time after reaching the crater current Ic.

Instead of decreasing the welding current at the end of welding at a predetermined rate, the welding current may be reduced from the main welding current Im to the crater current Ic at a predetermined time.

Further, in the above, the case where the present invention is applied to TIG arc welding has been described. However, the present invention can also be applied to manually operated plasma arc welding or semi-automatic arc welding.

[0025]

As described above, according to the present invention,
The first welding current and the second welding current are set in advance,
A period from the first closing signal to the second closing signal of the operation switch is set as a first period, the first welding current is supplied, and a period from the second closing signal to the next opening signal is provided. Is supplied as the second period, the second welding current is supplied, and the operation is shifted to the first period again by the open signal, and thereafter, the first period and the second period are alternated by the open / close signal of the operation switch. In the arc welding machine that controls to switch to, a monitoring circuit that monitors the time interval of the closing signal is provided,
When the closing signal is repeated within a predetermined time, the welding is controlled to end, so that the quality of the welding end portion in repeated welding can be improved without increasing the number of operation switches. it can.

[Brief description of the drawings]

FIG. 1 is a control circuit configuration diagram of an arc welding machine according to the present invention.

FIG. 2 is a flowchart illustrating a control procedure according to the present embodiment.

FIG. 3 is a flowchart showing an operation of the monitoring circuit 20;

FIG. 4 is a diagram showing a relationship between an open / close signal of an operation switch and a welding current.

FIG. 5 is a control circuit configuration diagram of a conventional arc welding machine.

FIG. 6 is a diagram showing an opening / closing signal, a welding current value, and an opening / closing operation of a solenoid valve by an operation switch in each conventional welding sequence.

FIG. 7 is a diagram showing an example of adjusting a welding current value according to a welding period.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Operation switch 3 Changeover switch 20 Monitoring circuit

Claims (3)

[Claims] A first welding current and a second welding current are set in advance, and a period from a first closing signal to a second closing signal of an operation switch is set as a first period. 1
Is supplied, the second welding current is supplied by setting a period from the second closing signal to the next opening signal as a second period, and the operation returns to the first period by the opening signal. Thereafter, a monitoring circuit for monitoring a time interval of a closing signal is provided in an arc welding machine which controls so as to alternately switch the first period and the second period by an opening / closing signal of the operation switch. An arc welding machine characterized in that when it is repeated within a predetermined time, the welding is controlled to end. 2. The arc welding machine according to claim 1, wherein the predetermined time is 0.5 seconds. 3. The arc welding machine according to claim 1, wherein the welding current is gradually reduced at the end of welding.