CN104526130A - Alternating current TIG welding method - Google Patents

Abstract

The present invention provides an alternating current TIG welding method of performing welding by alternate repetition of a straight polarity period and a reverse polarity period, by which it is possible to prevent a semiconductor element from being damaged because a surge voltage caused by a switching at the time of a polarity inversion is not generated by detecting a contact of a TIG electrode with an object to be welded during welding and, in the case where the TIG electrode is in contact with the object to be welded, inhibiting commutation from one polarity period to the other polarity period.

Description

AC-TIG WELDING welder

The application is international application no PCT/JP2011/003663, and thenational phase application number 201180004238.6, June 28 2011 applying date, denomination of invention are the divisional application of the application of alternating current TIG welding method.

Technical field

The present invention relates to and alternately repeat reversed polarity and positive polarity and the AC-TIG WELDING welder that carries out arc welding.

Background technology

In recent years, for the consideration to environment, in building and vehicle etc., utilize light weight and the good aluminium of recycling property and magnesium material more, often utilize AC-TIG WELDING welder when forming it and engaging.AC-TIG WELDING welder is the device (for example, referring to patent document 1) alternately repeating reversed polarity and positive polarity and carry out arc welding.

Especially, generating the operation field of building, needing to use big current to carry out operation.In big current AC welding, especially when want to extend export cable, the surge voltage produced when the switch during polarity upset of AC welding becomes large.There are the following problems: sometimes make the semiconductor element forming quadratic transformation device breakage can occur because of the size of this surge voltage.

Therefore, in the past, in order to carry out the protection of semiconductor element; implement following countermeasure, that is, before polarity upset, be controlled to low current (such as below 100A); under the state of this low current, carry out the switch of polarity upset, thus the surge voltage of generation is suppressed low.

But in operator's error, or when workpiece accuracy, clamp precision difference, in weld job, TIG electrode and welding object thing come in contact (this situation being called " electric pole short circuit " or " short circuit ") sometimes.Further, under short-circuit condition, the reduction degree of welding current becomes slow compared with under conditions at the arc.Therefore, there is following situation: if namely produce short circuit, under the state that electric current does not fully reduce before polarity upset, polarity upset occurs.There are the following problems: namely cause the semiconductor element as the constitutive requirements of the quadratic transformation device forming TIG welder to occur because of the size of surge voltage produced when the switch when the polarity upset of this AC welding damaged.

Next, the action of Fig. 8 and Fig. 9 to AC-TIG WELDING welder usual since has in the past been utilized to be described.In addition, the figure of Fig. 8 to be the figure of the brief configuration of the AC-TIG WELDING welder represented in the past, Fig. 9 be time variations of the welding current waveform represented in AC-TIG WELDING welder in the past.

The action of Fig. 9 to the AC-TIG WELDING welder formed as shown in Figure 8 is utilized to be described.In addition, in the following description, to during employing reversed polarity and the example of the AC-TIG WELDING welder of the non-consumable electrode formula alternately repeating during positive polarity and weld be described.

In fig. 8, AC-TIG WELDING welder 101 possesses: welding efferent 102, welding control part 103, current detecting part 104, configuration part 107, first timing unit 108.Further, AC-TIG WELDING welder 101 with possess the welding torch 110 of electrode 109 and be electrically connected as the mother metal 112 of welding object thing, and supply electric power between electrode 109 and mother metal 112, between electrode 109 and mother metal 112, produce electric arc 111 thus.

In addition, in the Fig. 9 of time variations representing welding current waveform, during TEN represents positive polarity, during TEP represents reversed polarity, TP1 represents between the positive polarity peak period, during TB1 represents positive polarity base value, TP2 represents between the reversed polarity peak period, during TB2 represents reversed polarity base value.In addition, IENP represents positive polarity peak point current, IEPP represents reversed polarity peak point current, IENB represents positive polarity background current, IEPB represents reversed polarity background current, IEN1 represents welding current (electric current during the positive polarity under short-circuit condition) before polarity upset, and IEP1 represents welding current (electric current during the reversed polarity under short-circuit condition) before polarity upset.In addition, E1 represents the moment be short-circuited, and E2 represents the moment that electric arc occurs again.

In fig. 8, the source power supply (such as, three-phase 200V etc.) be input as from outside supply of the welding efferent 102 of AC-TIG WELDING welder 101.Welding efferent 102 carries out being arranged on not shown primary transducer action and the action of quadratic transformation device of the inside of welding efferent 102 according to the control signal from welding control part 103, thus suitably switches positive polarity and reversed polarity and export the weldingvoltage and welding current that are suitable for welding.

Primary transducer is usually by by not shown IGBT (Insulated Gate Bipolar Transistor), not shown MOSFET (Metal-Oxide Semiconductor Field Effect Transistor), the not shown commutation diode of PWM (Pulse Width Modulation) action or phase shift action drives, smoothly use electrolytic capacitor, electric power conversion transformer etc. to form.

In addition, quadratic transformation device is made up of the not shown half-bridge employing IGBT or full-bridge usually, thus switches output polarity.

At this, positive polarity refers to, the moving direction of the electronics in arc-plasma is the direction from electrode 109 towards mother metal 112, and electrode 109 is for negative and mother metal is positive situation.In addition, reversed polarity refers to, the moving direction of the electronics in arc-plasma is the direction from mother metal 112 towards electrode 109, and electrode 109 is for just and mother metal 112 is negative situation.

The configuration part 107 be made up of CPU etc. sets TP1 (such as 9.5msec) between the positive polarity peak period, positive polarity base value period TB1 (such as 0.5msec), TP2 (such as 3.81msec), reversed polarity base value period TB2 (such as 0.47msec), positive polarity peak point current IENP (such as 400A), reversed polarity peak point current IEPP (such as-400A), positive polarity background current IENB (such as 100A), reversed polarity background current IEPB (such as 100A) between the reversed polarity peak period, and exports to welding control part 103.In addition, setting can input each parameter by operator and set, also can according to the setting electric current set separately (virtual value or mean value), frequency and utilize form or mathematical expression etc. automatically to set.

The first timing unit 108 be made up of CPU etc. measured the time counted from during positive polarity and during reversed polarity, and the current detecting part 104 be made up of CT etc. detects welding current.

The welding current value that the elapsed time that welding control part 103 measures according to the output of configuration part 107, the first timing unit 108, current detecting part 104 detect and output instruction signal is exported to welding efferent 102.Output instruction signal exports to welding efferent 102 by welding control part 103, described output instruction signal be between the positive polarity peak period in output cathode peak point current, during positive polarity base value in export the positive polarity background current lower than positive polarity peak point current, between the reversed polarity peak period in export reversed polarity peak point current, during reversed polarity base value in export the instruction of (absolute value little) reversed polarity background current lower than reversed polarity peak point current.

Output electrode, according to the output instruction signal from welding control part 103, as action during positive polarity in during making positive polarity, and is switched to electronics from electrode 109 to the direction of mother metal 112 movement by the action of quadratic transformation device by welding efferent 102.As action during reversed polarity in during making reversed polarity, and output electrode is switched to electronics from mother metal 112 to the direction of electrode 109 movement.

In addition, welding efferent 102 makes output cathode peak point current (such as, 400A) between the positive polarity peak period by the action of primary transducer, output cathode background current (such as, 100A) in during positive polarity base value.Further, welding efferent 102 is middle between the reversed polarity peak period exports reversed polarity peak point current (such as ,-400A), exports reversed polarity background current (such as ,-100A) in during reversed polarity base value.

The welding current that welding efferent 102 exports, weldingvoltage are powered to the welding torch 110 be connected with AC-TIG WELDING welder 101, and produce electric arc 111 between the welding object thing such as front end and aluminium and mother metal 112 of the TIG electrode be made up of tungsten etc. and electrode 109, and carry out AC-TIG WELDING welding.

Next, Fig. 9 is utilized to be described the action in AC-TIG WELDING welding in the past and welding current waveform.

As shown in Figure 9, before the moment E1 be short-circuited, at positive polarity period TEN, between the positive polarity peak period, TP1 terminates and to when positive polarity base value period, TB1 divided a word with a hyphen at the end of a line, welding current is reduced to positive polarity background current IENB (such as 100A) from positive polarity peak point current IENP (such as 400A).At the end of positive polarity base value period TB1, welding current is divided a word with a hyphen at the end of a line to reversed polarity period TEP.

In addition, at reversed polarity period TEP, between the reversed polarity peak period, TP2 terminates and to when reversed polarity base value period, TB2 divided a word with a hyphen at the end of a line, welding current from reversed polarity peak point current IEPP (such as,-400A) be reduced to reversed polarity background current IEPB (such as ,-100A).At the end of reversed polarity base value period TB2, welding current is divided a word with a hyphen at the end of a line to positive polarity period TEN.

So, before polarity upset, by making welding current be reduced to positive polarity background current IENB as target instruction target word value or reversed polarity background current IEPB, thus the surge voltage produced because of the switch of quadratic transformation device during polarity upset is suppressed low (such as, about 300V).Thus, the semiconductor element forming the quadratic transformation device of welding efferent 102 can not be damaged.

Next, the action of Fig. 9 to welding current waveform during being short-circuited of electrode 109 and mother metal 112 in AC-TIG WELDING welding is in the past used to be described.

As shown in Figure 9, in the positive polarity period TEN in the short circuit after there occurs the moment E1 of short circuit, to when dividing a word with a hyphen at the end of a line during positive polarity base value, welding current becomes positive polarity background current IENB to make to terminate between the positive polarity peak period to send instruction.But welding current cannot be reduced to positive polarity background current IENB (such as, 100A) from positive polarity peak point current IENP (such as, 400A).Further, welding current is only reduced to welding current IEN1 (such as, 300A) before the polarity upset larger than positive polarity background current IENB, divides a word with a hyphen at the end of a line during reversed polarity with the state of welding current IEN1 (such as, 300A) before polarity upset.In addition, this reason is in rear explanation.

In addition, when short circuit duration with mother metal 112 of electrode 109, at reversed polarity period TEP, send instruction to make to terminate between the reversed polarity peak period to when dividing a word with a hyphen at the end of a line during reversed polarity base value, welding current becomes reversed polarity background current IEPB.But welding current cannot be reduced to reversed polarity background current IEPB (such as ,-100A) from reversed polarity peak point current IEPP (such as ,-400A).Further, welding current is only reduced to welding current IEP1 (such as ,-300A) before the polarity upset larger than reversed polarity background current IEPB, divides a word with a hyphen at the end of a line during positive polarity with the state of welding current IEP1 (such as ,-300A) before polarity upset.In addition, this reason is in rear explanation.

Such as, welding current is made promptly from reversed polarity peak point current IEPP (such as at needs,-400A) rise to reversed polarity background current IEPB (such as,-100A) when, the primary transducer of welding efferent 102 stops, and welding efferent 102 output voltage exports 0V.Therefore, under conditions at the arc, by arc resistance, welding current is increased sharply.But at electrode 109 with under the short-circuit condition of mother metal 112 short circuit, arc resistance becomes 0, and therefore welding current can not promptly increase.Therefore, the welding current before polarity upset cannot be increased to positive polarity background current IENB or the reversed polarity background current IEPB of target instruction target word value.

And, at such electrode 109 with under the short-circuit condition of mother metal 112 short circuit, before polarity upset before welding current IEN1 or polarity upset welding current IEP1 state under there is polarity upset, before described polarity upset, before welding current IEN1 or polarity upset, welding current IEP1 is the electric current high with absolute value compared with the positive polarity background current IENB of target instruction target word value or reversed polarity background current IEPB.Therefore, the surge voltage that the switch because of quadratic transformation device produces uprises (such as, about 600V), and the semiconductor element forming quadratic transformation device may be damaged.

In addition, the outlet side of AC-TIG WELDING welder 101 is connected with and extends cable and cables extend is used under such circumstances (such as, length 40m), cable institute with inductance become greatly.Therefore, the surge voltage of generation raises further, and the danger of semiconductor element breakage improves further.

As mentioned above, in the prior art, if the short circuit of generating electrodes 109 and mother metal 112 in the operation of the big current circulation of AC-TIG WELDING welding, then the absolute value of welding current cannot promptly reduce, and the absolute value of the welding current before therefore cannot making polarity upset is reduced to positive polarity background current IENB or the reversed polarity background current IEPB of target instruction target word value.In addition, for above-mentioned reasons, before being the polarity upset high with absolute value compared with the positive polarity background current IENB of target instruction target word value or reversed polarity background current IEPB electric current before welding current IEN1 or polarity upset welding current IEP1 state under there is polarity upset.

Thus, the surge voltage produced because of the switch of quadratic transformation device uprises (such as, about 600V), there is the problem of the semiconductor element breakage forming quadratic transformation device.

As mentioned above, for AC-TIG WELDING welder in the past, if at big current (such as, the electric current of more than 300A, below 500A) short circuit of generating electrodes and mother metal in the operation of circulating, then carry out polarity upset under the state that welding current cannot fully reduce before polarity upset.Therefore, the surge voltage that the switch because of quadratic transformation device produces uprises, and there is the problem of the semiconductor element possibility breakage forming quadratic transformation device.

[look-ahead technique document]

[patent document]

[patent document 1] Japanese Unexamined Patent Publication 2-235574 publication

Summary of the invention

A kind ofly the AC-TIG WELDING welder of the high-quality of the semiconductor element breakage forming converter also can be suppressed when there occurs the short circuit of electrode and mother metal in the welding of big current circulation even if the invention provides.

In order to solve the problem, AC-TIG WELDING welder of the present invention possesses: welding efferent, and it exports weldingvoltage; Welding control part, it controls described welding efferent; Voltage detection department, it detects described weldingvoltage; AS detection unit, it judges short-circuit condition or conditions at the arc according to the testing result of described voltage detection department, and result of determination is exported to described control part, described control part is when described result of determination is short circuit judgement, forbid to the change of current between the polarity epoch of the opposing party between the polarity epoch of a side, thus the surge voltage produced because of switch during polarity upset can not be produced.

As described above, according to the present invention, when there occurs the contact of TIG electrode and welding object thing in welding, by forbidding in the short-circuit state polarity upset occurring, thus also can not produce the surge voltage produced because of the reason of switch during polarity upset.Thereby, it is possible to realize preventing the AC-TIG WELDING of the high-quality of semiconductor element breakage from welding.

Accompanying drawing explanation

Fig. 1 is the figure of the brief configuration representing the AC-TIG WELDING welder used in the alternating current TIG welding method of embodiments of the present invention 1.

Fig. 2 is the figure of the time variations of the welding current waveform represented in the alternating current TIG welding method of embodiments of the present invention 1.

Fig. 3 is the figure of the brief configuration representing the AC-TIG WELDING welder used in the alternating current TIG welding method of embodiments of the present invention 2.

Fig. 4 is the figure of the time variations of the welding current waveform represented in the alternating current TIG welding method of embodiments of the present invention 2.

Fig. 5 is the figure of the time variations of the welding current waveform represented in the alternating current TIG welding method of embodiments of the present invention 2.

Fig. 6 is the figure of the brief configuration representing the AC-TIG WELDING welder used in the alternating current TIG welding method of embodiments of the present invention 3.

Fig. 7 is the figure of the time variations of welding current waveform in the alternating current TIG welding method representing embodiments of the present invention 3.

Fig. 8 is the figure of the brief configuration of the AC-TIG WELDING welder represented in the past.

Fig. 9 is the figure of the time variations of the welding current waveform of the AC-TIG WELDING welder represented in the past.

Detailed description of the invention

Below, with reference to accompanying drawing, embodiments of the present invention are described.In figures in the following, identical symbol is marked to identical constitutive requirements, therefore there is situation about omitting the description.

(embodiment 1)

To be the figure of the brief configuration representing the AC-TIG WELDING welder used in the alternating current TIG welding method of present embodiment 1, Fig. 2 be Fig. 1 represents the figure of the time variations of welding current waveform in the alternating current TIG welding method of present embodiment 1.For the AC-TIG WELDING welder formed as shown in Figure 1, utilize the time variations of the welding current waveform of Fig. 2 that its action is described.

Below, for during alternately repeating reversed polarity and the AC-TIG WELDING welder carrying out the non-consumable electrode formula of welding during positive polarity be described.

As shown in Figure 1, AC-TIG WELDING welder 1 is configured to possess: welding efferent 2, welding control part 3, current detecting part 4, voltage detection department 5, AS detection unit 6, configuration part 7, first timing unit 8.At this, welding efferent 2 carries out welding and exports.Welding control part 3 controls welding efferent 2.Current detecting part 4 detects welding current.Voltage detection department 5 detects weldingvoltage.AS detection unit 6 according to the testing result of voltage detection department 5 detect be electrode 9 and mother metal 12 short circuit short-circuit condition or between electrode 9 and mother metal 12, create the conditions at the arc of electric arc.Configuration part 7 sets welding condition etc.First timing unit 8 pairs time measured.

Further, in AC-TIG WELDING welder 1, the welding torch 10 possessing electrode 9 is electrically connected with the mother metal 12 as welding object thing, by supplying electric power between electrode 9 and mother metal 12, thus produces electric arc 11 between electrode 9 and mother metal 12.

In addition, in the Fig. 2 representing current waveform, during TEN represents positive polarity, during TEP represents reversed polarity, TP1 represents between the positive polarity peak period, and during TB1 represents positive polarity base value, TP2 represents between the reversed polarity peak period, during TB2 represents reversed polarity base value, TEN1 represent in during positive polarity be short-circuited before during.

In addition, IENP represents positive polarity peak point current, IEPP represents reversed polarity peak point current, IENB represents positive polarity background current, IEPB represents reversed polarity background current, IEP2 represents welding current (electric current at the end of during the reversed polarity under short-circuit condition), and IEPBABS represents the absolute value of reversed polarity background current, and IEPPABS represents the absolute value of reversed polarity peak point current.

In addition, E1 represents the moment be short-circuited, and E2 represents the moment that electric arc regenerates, the moment terminated during E6 represents reversed polarity.

In FIG, the welding efferent 2 of AC-TIG WELDING welder 1, using the source power supply (three-phase 200V etc.) from externally fed as input, carries out welding the not shown primary transducer action in efferent 2 and the action of quadratic transformation device according to the output from welding control part 3.Thus, weld efferent 2 suitably switch positive polarity and reversed polarity and export the weldingvoltage and welding current that are suitable for welding.

Primary transducer is formed by by not shown IGBT (Insulated Gate Bipolar Transistor), the not shown MOSFET (Metal-Oxide Semiconductor Field Effect Transistor) of PWM (Pulse Width Modulation) action or phase shift action drives, 1 time not shown commutation diode, level and smooth electrolytic capacitor or electric power conversion transformer etc. usually.

In addition, quadratic transformation device usually uses not shown IGBT and is made up of half-bridge or full-bridge, and it switches output polarity.

At this, positive polarity refers to, the moving direction of the electronics in arc-plasma is the direction from electrode 9 towards mother metal 12, and electrode 9 is for negative and mother metal is positive situation.In addition, reversed polarity refers to, the moving direction of the electronics in arc-plasma is the direction from mother metal 12 towards electrode 9, and electrode 9 is for just and mother metal 12 is negative situation.

The configuration part 7 be made up of CPU etc. to set between the positive polarity peak period TP1 (such as, 9.5msec), positive polarity base value period TB1 (such as, 0.5msec), between the reversed polarity peak period, TP2 is (such as, 3.81msec), reversed polarity base value period TB2 (such as, 0.47msec), positive polarity peak point current IENP (such as, 400A), reversed polarity peak point current IEPP (such as,-400A), positive polarity background current IENB (such as, 100A), reversed polarity background current IEPB (such as,-100A), and export to welding control part 3.In addition, setting can input each parameter by operator and set, also can according to the setting electric current set separately (virtual value or mean value), frequency and utilize form or mathematical expression etc. automatically to set.

The first timing unit 8 be made up of CPU etc. measured the time counted from during positive polarity and time of counting from during reversed polarity.The current detecting part 4 be made up of CT etc. detects welding current.

Welding control part 3 is according to the output of configuration part 7, the elapsed time that first timing unit 8 measures, current detecting part 4 detect welding current value and by output instruction signal to welding efferent 2 export, described output instruction signal is middle output cathode peak point current between the positive polarity peak period, the positive polarity background current lower than positive polarity peak point current is exported in during positive polarity base value, reversed polarity peak point current is exported between the reversed polarity peak period, the instruction of (absolute value little) reversed polarity background current lower than reversed polarity peak point current is exported in during reversed polarity base value.

Output electrode, according to the output instruction signal from welding control part 3, as action during positive polarity in during making positive polarity, and is switched to electronics from electrode 9 to the direction of mother metal 12 movement by the action of quadratic transformation device by welding efferent 2.As action during reversed polarity in during making reversed polarity, and output electrode is switched to electronics from mother metal 12 to the direction of electrode 9 movement.

In addition, during welding efferent 2 to be made between the positive polarity peak period by the action of primary transducer, output cathode peak point current (such as, 400A), in during positive polarity base value, output cathode background current (such as, 100A), reversed polarity peak point current (such as ,-400A) is exported between the reversed polarity peak period, reversed polarity background current (such as ,-100A) is exported in during reversed polarity base value.

The welding current exported by welding efferent 2, weldingvoltage are powered to the welding torch 10 be connected with AC-TIG WELDING welder 1, and produce electric arc 11 between mother metal 12 as welding object thing of the front end and aluminium etc. of the TIG electrode be made up of tungsten etc. and electrode 9, and carry out AC-TIG WELDING welding.

To be made up of CT etc. and the voltage detection department 5 measuring voltage between the lead-out terminal of AC-TIG WELDING welder 1 detects weldingvoltage.

The AS detection unit 6 be made up of CPU etc. inputs the voltage detection signal from voltage detection department 5 and calculates the absolute value of voltage detection signal.Further, consider that the absolute value of voltage detection signal arrives the situation of the detection level (such as, 10V) that (being reduced to) presets during being judged to be conditions at the arc.In this case, be judged to be that electrode 9 contacts with the mother metal 12 as welding object thing (being called electric pole short circuit or short circuit), make AS signal be that short circuit judges (low level).In addition, consider that the absolute value of voltage detection signal arrives the situation of the detection level (such as, 15V) that (being increased to) presets during being judged to be short-circuit condition.In this case, be judged to be that electrode 9 disconnects with the contact (short circuit) as the mother metal 12 of welding object thing and produces electric arc (being called that electric arc regenerates or conditions at the arc), and make AS signal be that electric arc judges (high level).

That welding control part 3 input controlling welding efferent 2 represents short-circuit condition or conditions at the arc, that AS detection unit 6 exports AS signal.When AS signal is short circuit judgement (low level), welding control part 3 controls welding efferent 2, with make reach to carry out between the polarity epoch of a side to moment of the change of current between the polarity epoch of the opposing party time, also forbid between the polarity epoch of a side to the change of current between the polarity epoch of the opposing party.Further, maintain the change of current when being continuously short circuit as AS signal and judging (low level) to forbid.

In addition, when AS signal is electric arc judgement (high level), arrive to carry out between the polarity epoch of a side to moment of the change of current between the polarity epoch of the opposing party time, welding control part 3 controls welding efferent 2 can carry out between the polarity epoch of a side to the change of current between the polarity epoch of the opposing party.In addition, for short circuit judges and under maintaining the state that the change of current forbids, even if become electric arc when judging, welding control part 3 also controls welding efferent 2 can carry out to the change of current between the polarity epoch of the opposing party between the polarity epoch of a side, and its details is aftermentioned.

Next, Fig. 2 is utilized to be described to the action of the change of current between the polarity epoch of the opposing party and welding current waveform between the polarity epoch of a side forbidding when there occurs short circuit in AC-TIG WELDING welding.

In fig. 2, before arriving the moment E1 be short-circuited, at positive polarity period TEN, when between the positive polarity peak period, TP1 terminates and to when positive polarity base value period, TB1 divided a word with a hyphen at the end of a line, welding current from positive polarity peak point current IENP (such as, 400A) be reduced to positive polarity background current IENB (such as, 100A), and divide a word with a hyphen at the end of a line to reversed polarity period TEP at the end of positive polarity base value period TB1.

In addition, at reversed polarity period TEP, when between the reversed polarity peak period, TP2 terminates and to when reversed polarity base value period, TB2 divided a word with a hyphen at the end of a line, the absolute value of welding current from reversed polarity peak point current IEPP (such as,-400A) be reduced to reversed polarity background current IEPB (such as,-100A), and divide a word with a hyphen at the end of a line to positive polarity period TEN at the end of reversed polarity base value period TB2.

Under the short-circuit condition that there occurs after the moment E1 of short circuit shown in Fig. 2, at positive polarity period TEN, send instruction and divide a word with a hyphen at the end of a line to positive polarity base value period TB1 to make TP1 between the positive polarity peak period terminate thus make welding current become positive polarity background current IENB.In this case, electric current cannot from positive polarity peak point current IENP (such as, 400A) be reduced to positive polarity background current IENB (such as, 100A), welding current IEN2 (such as, 300A) before being only reduced to the polarity upset larger than positive polarity background current IENB and terminate positive polarity period TEN.In addition, the reason that electric current is difficult to reduce under electrode 9 short-circuit condition with mother metal 12 is, if the short circuit of generating electrodes 109 and mother metal 112 in the operation passed through at the big current of AC-TIG WELDING welding, then welding current cannot promptly reduce.This reason is identical with the reason utilizing Fig. 9 to illustrate in the introduction.

Further, in the finish time of positive polarity period TEN, owing to being continuously the state of electrode 9 and mother metal 12 short circuit from moment E1, therefore AS detection unit 6 carries out short circuit judgement, and welding control part 3 forbids the change of current between the polarity epoch to the opposing party.In the case of figure 2, be prohibited from positive polarity to the change of current of reversed polarity.

So, because the change of current of polarity is prohibited, therefore can not carry out polarity upset under current state, the surge voltage produced because of the switch of the quadratic transformation device for polarity upset can not be produced.So the semiconductor element forming quadratic transformation device can not be damaged.

Further, as shown in Figure 2, keeping under the state of not carrying out polarity upset, welding instruction divides a word with a hyphen at the end of a line (polarity upset does not occur actual electric current) during reversed polarity.Now, reversed polarity peak point current (polarity upset does not occur) is suitable for the absolute value IEPPABS (such as, 400A) of reversed polarity peak point current.In addition, reversed polarity background current (polarity upset does not occur) is suitable for the absolute value IEPBABS (such as, 100A) of reversed polarity background current.

The welding current sent when instruction is divided a word with a hyphen at the end of a line to (polarity upset does not occur) during reversed polarity base value to make (polarity upset not occurring) between the reversed polarity peak period and terminate becomes reversed polarity background current IEPBABS.In this case, welding current still cannot be reduced to the absolute value IEPBABS (such as, 100A) of reversed polarity background current from the absolute value IEPPABS of reversed polarity peak point current (such as, 400A).Further, welding current is only reduced to welding current IEP2 (such as, 300A) before the value larger than the absolute value IEPBABS of reversed polarity background current and polarity upset, divides a word with a hyphen at the end of a line in this condition to positive polarity period TEN.

Now, owing to being continuously the state of electrode 9 and mother metal 12 short circuit from moment E1, therefore AS detection unit 6 carries out short circuit judgement, and welds the change of current between polarity epoch that control part 3 forbids to the opposing party.

So, because the change of current of polarity is as described above prohibited, therefore can not carries out polarity upset under the state that electric current is high, the surge voltage caused because of the switch of the quadratic transformation device for polarity upset can not be produced.So the semiconductor element forming quadratic transformation device can not be damaged.

Next, when utilizing Fig. 2 to illustrate to be short-circuited in AC-TIG WELDING welding and to make the change of current forbid continuing and disconnect in after this short circuit and make to produce electric arc (electric arc regeneration), enable the action carried out to the change of current between the polarity epoch of the opposing party between the polarity epoch of a side and welding current waveform.

The moment E2 of the electric arc regeneration shown in Fig. 2, becomes because electrode 9 disconnects with the short circuit of mother metal 12 state producing electric arc, and therefore AS detection unit 6 becomes electric arc judgement, and the change of current is carried out.

Current Control is by welding control part 3, the current waveform of the reference instant during repeating positive polarity with the moment of predetermined regulation and during reversed polarity.

At this, welding control part 3 controls welding efferent 2 in the following manner to carry out the change of current, that is, wait for the reference instant of the change of current from positive polarity to reversed polarity next time of the moment E2 of electric arc regeneration, at the moment E5 that positive polarity period TEN terminates, carry out the change of current from positive polarity to reversed polarity.

In addition, moment E5 has been conditions at the arc, fully reduces as shown in Figure 2 to the electric current before the reversed polarity change of current, therefore can not produce the problem of the surge voltage that the switch because of quadratic transformation device produces.

In addition, moment E4 shown in Fig. 2, when electric arc has regenerated, control in the following manner, namely, the moment E6 terminated at reversed polarity period TEP does not carry out the change of current, waits for the reference instant of the change of current from positive polarity to reversed polarity next time, and carries out the change of current at the moment E5 that positive polarity period TEN terminates.

As mentioned above, carrying out short circuit when situation about being short-circuited as the electrode 9 of TIG electrode and the mother metal 12 as welding object thing in welding being detected when judging, having forbidden between the polarity epoch of a side to the change of current between the polarity epoch of the opposing party.Thus, prevent from carrying out polarity upset under the state of big current, the large surge voltage occurred because the switch of quadratic transformation device during polarity upset produces can be suppressed.Consequently, the semiconductor element forming quadratic transformation device can be prevented damaged.

In addition; when excess voltage protection being set in AC-TIG WELDING welder in the object that the breakage for quadratic transformation device is protected; in AC-TIG WELDING welder 101 in the past; owing to still carrying out the change of current at electrode 109 with during mother metal 112 short circuit, so easily produce large surge voltage.Therefore, excess voltage protection action and AC-TIG WELDING welder 101 is easily stopped, weld job efficiency reduces.But, in the AC-TIG WELDING welder 1 of present embodiment 1, owing to forbidding the change of current at electrode 9 with during mother metal 12 short circuit, therefore, it is possible to suppress to produce large surge voltage.Therefore, it is possible to over-voltage suppression protection circuit action and make the situation that AC-TIG WELDING welder 1 stops, can preventing weld job efficiency from reducing.

Namely, alternating current TIG welding method of the present invention be alternately repeat positive polarity during with the alternating current TIG welding method carrying out during reversed polarity welding, the contact of TIG electrode and welding object thing is detected in welding, when TIG electrode contacts with welding object thing (when short circuit), forbid between the polarity epoch of a side to the change of current between the polarity epoch of the opposing party.

According to the method, by forbidding polarity upset in the short-circuit state, the surge voltage produced because of the reason of switch during polarity upset can not be produced.Thereby, it is possible to realize preventing the AC-TIG WELDING of the high-quality of semiconductor element breakage from welding.

In addition, also can be following method: the contact of TIG electrode and welding object thing namely detected in welding after, disconnect in the contact of TIG electrode and welding object thing and before producing electric arc, maintain the electric current in the moment that TIG electrode contacts with welding object thing.

According to the method, can not polarity upset be carried out under current state, the surge voltage that the switch because of the quadratic transformation device for polarity upset produces can not be produced.Thus, the semiconductor element forming quadratic transformation device can not be damaged.

In addition, also can be following method: when the contact of TIG electrode and welding object thing namely being detected in welding, make electric current be reduced to the current value lower than the current value in the moment of contact TIG electrode and welding object thing being detected.

According to the method, polarity upset can not be carried out under large current status, the surge voltage that the switch because of the quadratic transformation device for polarity upset produces can not be produced.Thus, the semiconductor element forming quadratic transformation device can not be damaged.

In addition, also can be following method: the contact of TIG electrode and welding object thing namely detected in welding after, if the disconnection of the contact of TIG electrode and welding object thing detected, then enable to carry out to the change of current between the polarity epoch of the opposing party between the polarity epoch of a side.

According to the method, can prevent from carrying out polarity upset under the state of big current, the generation of the large surge voltage that the switch because of quadratic transformation device during polarity upset can be suppressed to produce.Consequently, the semiconductor element forming quadratic transformation device can be prevented damaged.

In addition, also can be following method: the contact of TIG electrode and welding object thing namely detected in welding after, if the disconnection of the contact of TIG electrode and welding object thing detected, then by Current Control be become predetermined positive polarity during with reversed polarity during the current waveform of reference instant.

According to the method, can prevent from carrying out polarity upset under the state of big current, the appearance because of the large surge voltage produced by the switch of quadratic transformation device during polarity upset can be suppressed.Consequently, the semiconductor element forming quadratic transformation device can be prevented damaged.

In addition, in present embodiment 1, be illustrated for the situation that there occurs short circuit during positive polarity, but when being short-circuited during reversed polarity, by carrying out same control, also can play same effect.

(embodiment 2)

Fig. 3 is the figure of the brief configuration of the AC-TIG WELDING welder representing embodiments of the present invention 2, the figure of Fig. 4 to be the figure of the time variations of the welding current waveform representing embodiments of the present invention 2, Fig. 5 be time variations of the welding current waveform representing embodiments of the present invention 2.

In present embodiment 2, be described with the AC-TIG WELDING welder carrying out the non-consumable electrode formula of welding during positive polarity during alternately repeating reversed polarity.The action of the welding current waveform of Fig. 4 and Fig. 5 to the AC-TIG WELDING welder with the structure shown in Fig. 3 is utilized to be described.

In figure 3, AC-TIG WELDING welder 21 possesses short-circuit condition and reduces current settings portion 13, for setting electrode 9 and electric current during mother metal 12 short circuit.Possessing this short-circuit condition reduction current settings portion 13 this point is the difference with the AC-TIG WELDING welder 1 shown in Fig. 1 of embodiment 1.

In addition, in Fig. 4 and Fig. 5, electric current when IS represents electrode 9 and mother metal 12 short circuit and short-circuit condition reduce electric current.

In figure 3, the short-circuit condition reduction current settings portion 13 be made up of CPU etc. inputs the current signal as the AS signal of the output of AS detection unit 6 and the output as current detecting part 4, and setting is than detecting that the current value that electrode 9 is low with the current value in the moment of the short circuit of mother metal 12 and short-circuit condition reduce current IS.

Welding control part 3 inputs the output reducing current settings portion 13 as the AS signal of the output of AS detection unit 6 and short-circuit condition, welding current control is become short-circuit condition under the short-circuit condition of electrode 9 with mother metal 12 and reduces current IS.

In addition, in the AC-TIG WELDING welder 21 of present embodiment 2, calculate short-circuit condition according to the output current of current detecting part 4 in moment short circuit being detected and reduce current IS.In addition, the welding current instruction that also can keep according to welding control part 3 calculates and sets short-circuit condition and reduces current IS.

In addition, also the current value that presets can be set (such as, 100A) and a side lower in the welding current value in the moment of short circuit detected, the welding current value that also can set the moment by short circuit being detected be multiplied by preset be less than 1 coefficient (such as, 0.5) and the value obtained.

Next, when using Fig. 4 to be short-circuited to the moment E1 electrode 9 in AC-TIG WELDING welding and mother metal 12, forbid being described to the action of the change of current between the polarity epoch of the opposing party and welding current waveform between the polarity epoch of a side.

The moment E1 that there occurs short circuit shown in Fig. 4, AS detection unit 6 detects the short circuit of electrode 9 and mother metal 12 and carries out short circuit judgement.To the change of current between the polarity epoch of the opposing party between the polarity epoch that welding control part 3 was forbidden according to the output of AS detection unit 6 moment of short circuit namely being detected between the polarity epoch of a side.In the example of fig. 4, the change of current from positive polarity to reversed polarity is forbidden.

At electrode 9 with under the short-circuit condition of mother metal 12, the soldered control part 3 of welding current is controlled to be reduced to and reduces the short-circuit condition that sets of current settings portion 13 by short-circuit condition and reduce current IS (such as, 100A), this short-circuit condition reduces current IS is the current value lower than the current value (being positive polarity peak point current IENP and 400A in the case of figure 4) in the moment this short circuit being detected.

Next, Fig. 4 is used to be described the action of the permission change of current under the state of forbidding the change of current there occurs short circuit during electric arc regeneration and welding current waveform skill.

The moment E2 of the electric arc regeneration shown in Fig. 4, AS detection unit 6 carries out electric arc judgement, allow the change of current, and weld control part 3 and control welding current in the following manner, namely, according between polarity epoch short circuit being detected (in this case positive polarity period TEN) contrary polarity epoch between current waveform the starting of (reversed polarity period TEP), start to carry out Current Control.

In addition, for the control of the later electric current of moment E2 of electric arc regeneration, also can be as shown in Figure 5, at the moment E2 of electric arc regeneration, welding current is controlled to make by welding control part 3, according to the current waveform the starting of (in this case positive polarity period TEN) between polarity epoch short circuit being detected, start to carry out Current Control.

As previously discussed, according to the present embodiment, short circuit has been carried out when judging in welding, by forbidding the change of current between the polarity epoch to the opposing party, thus the appearance that suppress the large surge voltage that by the switch of quadratic transformation device during polarity upset produced same with embodiment 1.Thereby, it is possible to prevent the semiconductor element forming quadratic transformation device damaged.

In addition, under short circuit duration state, reduce current IS by electric current being reduced to the short-circuit condition lower than electric current during short-circuit detecting, thus unnecessary consumption of electrode and damage can be prevented.

In addition, owing to dividing a word with a hyphen at the end of a line to common AC welding immediately after electric arc regeneration, the recovery therefore to normal weld state is very fast, not easily produces weld defect.

Namely, alternating current TIG welding method of the present invention be alternately repeat positive polarity during and carry out the alternating current TIG welding method that welds during reversed polarity, consist of following method, namely, the contact of TIG electrode and welding object thing is detected in welding, when TIG electrode contacts with welding object thing (when short circuit), forbid between the polarity epoch of a side to the change of current between the polarity epoch of the opposing party.Further, the contact of TIG electrode and welding object thing detected in welding after, if the disconnection of the contact of TIG electrode and welding object thing detected, then enable to carry out to the change of current between the polarity epoch of the opposing party between the polarity epoch of a side.And, also can be following method: the contact of TIG electrode and welding object thing namely detected in welding after, if the disconnection of the contact of TIG electrode and welding object thing detected, then carry out Current Control, with become with from detect TIG electrode and welding object thing contact polarity epoch between start the identical current waveform of current waveform.

According to the method, suppress the appearance of the large surge voltage produced because of the switch of quadratic transformation device during polarity upset.Thereby, it is possible to prevent the semiconductor element forming quadratic transformation device damaged.

In addition, also can be following method: namely, the contact of TIG electrode and welding object thing detected in welding after, if the disconnection of the contact of TIG electrode and welding object thing detected, then control electric current, to make to become from the current waveform identical with the current waveform detected starting between polarity epoch contrary between the polarity epoch contacted of TIG electrode and welding object thing.

According to the method, the appearance of the large surge voltage that the switch because of quadratic transformation device during polarity upset can be suppressed to produce.Thereby, it is possible to prevent the semiconductor element forming quadratic transformation device damaged.

In addition, in present embodiment 2, be illustrated for situation about being short-circuited during positive polarity, but when being short-circuited during reversed polarity, same effect can be played by carrying out same control.

(embodiment 3)

Fig. 6 is the figure of the brief configuration of the AC-TIG WELDING welder representing embodiments of the present invention 3, Fig. 7 is the figure of the time variations of the welding current waveform representing embodiments of the present invention 3.

In present embodiment 3, for during alternately repeating reversed polarity and the AC-TIG WELDING welder carrying out the non-consumable electrode formula of welding during positive polarity be described.The action of the welding current waveform of Fig. 7 to the AC-TIG WELDING welder 31 with the structure shown in Fig. 6 is utilized to be described.

In figure 6, AC-TIG WELDING welder 31 possesses second timing unit 15 of welding output dwell time configuration part 14 and the time of measurement from being short-circuited when short circuit occurs.Possessing welding when this short circuit occurs and export dwell time configuration part 14 and this one side of the second timing unit 15, is the aspect different from the AC-TIG WELDING welder 1 shown in Fig. 1 of embodiment 1.

In addition, in the figure 7, TRES represents the time stopping welding exporting when short circuit occurs.E3 represents the moment from short circuit course of emergency TRES.

In figure 6, continue for the threshold value in the elapsed time from being short-circuited and starting, namely, during electrode 9 and the contact of mother metal 12 continue for regulation in welding, weld when the short circuit be made up of occurs when output dwell time configuration part 14 sets the short circuit generation of the specified time limit exported as stopping welding welding output dwell time TRES CPU etc.The second timing unit 15 be made up of CPU etc. measures the time from being short-circuited.

When welding control part 3 inputs AS detection unit 6, short circuit occurs, welding exports the output of dwell time configuration part 14 and the second timing unit 15.When in welding electrode 9 during continue for regulation with the contact (short circuit) of mother metal 12 be short circuit occur time weld export dwell time TRES (such as, lsec) time, welding control part 3 control welding efferent 2 and make welding export stop.

Next, use Fig. 7 to illustrate to forbid when moment E1 there occurs the short circuit of electrode 9 and mother metal 12 between the polarity epoch of a side to the action of the change of current between the polarity epoch of the opposing party and welding current waveform in AC-TIG WELDING welding.

The moment E1 that there occurs short circuit shown in Fig. 7, AS detection unit 6 goes out electrode 9 according to the output detections of voltage detection department 5 and mother metal 12 there occurs short circuit and carries out short circuit judgement.So, the change of current that control part 3 is forbidden to the opposing party between polarity epoch according to the output of AS detection unit 6 is welded.In the example in figure 7, be prohibited from positive polarity to the change of current of reversed polarity.

After short circuit electrode 9 and mother metal 12 being detected, disconnect with the short circuit of mother metal 12 at electrode 9 and before producing electric arc, weld the current value (in this case the value of positive polarity peak point current IENP) that welding current control is become to maintain the moment E1 be short-circuited by control part 3.

In addition, when welding control part 3 inputs AS detection unit 6, short circuit occurs, welding exports the output of dwell time configuration part 14 and the second timing unit 15, from the moment E1 be short-circuited, continue for welding when short circuit occurs in short circuit and export dwell time TRES (such as, lsec), when, welding is stopped to export.

So, when there occurs long short circuit, being judged to be abnormal and stopping welding exporting.Thus, abnormal short circuit current can not be made to continue circulation, weld job can be carried out safely.

As mentioned above, according to the present embodiment 3, in welding, carry out short circuit when judging, forbid the change of current between the polarity epoch to the opposing party.Thus, the generation of the large surge voltage preventing the switch because of quadratic transformation device during polarity upset from producing, can prevent the semiconductor element forming quadratic transformation device damaged.

Namely, alternating current TIG welding method of the present invention be alternately repeat positive polarity during with the alternating current TIG welding method carrying out during reversed polarity welding, consist of following method, namely, contacting of TIG electrode and welding object thing is detected in welding, when TIG electrode contacts with welding object thing (when short circuit), forbid between the polarity epoch of a side to the change of current between the polarity epoch of the opposing party.Further, stop welding the method exported when also can be configured to during in welding, TIG electrode continue for regulation with the contact of welding object thing.

According to the method, abnormal short circuit current can not be made to continue circulation, weld job can be carried out safely.

In addition, when short circuit occurs, welding exports dwell time TRES can be the fixed value preset, and also can be the value based on exporting welding current.In addition, in present embodiment 3, be illustrated for the situation that there occurs short circuit during positive polarity, but when being short-circuited during reversed polarity, also can play same effect by carrying out same control.

[industrial utilizability]

As mentioned above, application invention there occurs the contact of electrode and welding object thing in based on the welding of big current, forbid that output polarity overturns in the short-circuit state.Thereby, it is possible to avoid the surge voltage that occurs because the switch of polarity upset produces and prevent semiconductor element breakage.Thus, as the automotive field and building field etc. that carry out such as AC-TIG WELDING welding procedure, especially carry out the generation employing aluminium or magnesium material the alternating current TIG welding method in field industrially useful.

[symbol description]

1,21,31 AC-TIG WELDING welders

2 welding efferents

3 welding control parts

4 current detecting parts

5 voltage detection departments

6 AS detection units

7 configuration parts

8 first timing unit

9 electrodes

10 welding torches

11 electric arcs

12 mother metals

13 short-circuit conditions reduce current settings portion

When 14 short circuits occur, welding exports dwell time configuration part

15 second timing unit

Claims (10)

1. an AC-TIG WELDING welder, it possesses:

Welding efferent, it exports weldingvoltage;

Welding control part, it controls described welding efferent;

Voltage detection department, it detects described weldingvoltage;

AS detection unit, it judges short-circuit condition or conditions at the arc according to the testing result of described voltage detection department, and result of determination is exported to described control part,

Described control part when described result of determination be short circuit judge, forbid to the change of current between the polarity epoch of the opposing party between the polarity epoch of a side, thus the surge voltage produced because of switch during polarity upset can not be produced.

2. AC-TIG WELDING welder according to claim 1, is characterized in that,

Described welding efferent also exports welding current,

Described AC-TIG WELDING welder also possesses:

Current detecting part, it detects described welding current;

Configuration part, it sets welding condition, and described welding condition is exported to described control part;

First timing unit, it measured the time, and exported to described control part.

3. AC-TIG WELDING welder according to claim 2, is characterized in that,

This AC-TIG WELDING welder also possesses short-circuit condition and reduces current settings portion,

The input of current settings portion is reduced from the described result of determination of described AS detection unit and the current signal from described current detecting part in described short-circuit condition, and the short-circuit condition reduction electric current that setting is lower than described welding current.

4. AC-TIG WELDING welder according to claim 2, is characterized in that,

This AC-TIG WELDING welder also possesses:

Second timing unit, its measurement short circuit time of origin, and export to described control part;

When short circuit occurs, welding exports dwell time configuration part, and when its setting short circuit occurs, welding exports dwell time, and exports to described control part.

5. AC-TIG WELDING welder according to claim 1 and 2, is characterized in that,

Described control part, when described result of determination is short circuit judgement, before generation electric arc, maintains the electric current creating the moment of described short circuit.

6. the AC-TIG WELDING welder according to claim 3 or 4, is characterized in that,

Described control part, when described result of determination is short circuit judgement, makes described welding current become described short-circuit condition and reduces electric current.

7. AC-TIG WELDING welder according to any one of claim 1 to 4, is characterized in that,

If from short circuit, described result of determination judges that being changed to electric arc judges, then described control part enables to carry out to the change of current between the polarity epoch of the opposing party between the polarity epoch of a side, Current Control is become and the current waveform identical from the current waveform carried out starting between polarity epoch that described short circuit judges.

8. AC-TIG WELDING welder according to any one of claim 1 to 4, is characterized in that,

If from short circuit, described result of determination judges that being changed to electric arc judges, then described control part enables to carry out to the change of current between the polarity epoch of the opposing party between the polarity epoch of a side, Current Control is become the current waveform identical with the current waveform from starting during the opposite polarity carried out between polarity epoch that described short circuit judges.

9. AC-TIG WELDING welder according to any one of claim 1 to 4, is characterized in that,

If from short circuit, described result of determination judges that being changed to electric arc judges, then described control part enables to carry out to the change of current between the polarity epoch of the opposing party between the polarity epoch of a side, the current waveform of the reference instant during Current Control is become predetermined positive polarity and during reversed polarity.

10. AC-TIG WELDING welder according to claim 4, is characterized in that,

Described control part is arrive during short circuit judges when when described short circuit occurs, welding exports dwell time to stop welding exporting in described result of determination.