Double-shield TIG welding method

Abstract

To provide a double-shield TIG welding method that reduces consumption of gas, when welding by supplying a welding-current of a pulse waveform.SOLUTION: In a double-shield TIG welding method, a welding torch WT comprising an inner nozzle 4 ejecting inner gas 7 and an outer nozzle 5 ejecting outer gas 9 is used, and a welding-current Iw of a pulse waveform that is formed from a peak current in a peak period and a base current in a base period is supplied to perform welding. In the double-shield TIG welding method, the inner gas 7 is ejected in the peak period, but ejection of the inner gas 7 is stopped in the base period.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a double shielded TIG welding method. [Background technology]

[0002] A double-shielded TIG welding method is commonly used in which a welding torch equipped with an inner nozzle for ejecting an inner gas and an outer nozzle for ejecting an outer gas is used to pass a welding current through the welding torch (see, for example, Patent Document 1). As the inner gas and the outer gas, an inert gas such as argon or helium is used. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-15048 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the double shielded TIG welding method, two types of gas, an inner gas and an outer gas, are used, so the gas consumption is greater than in the normal TIG welding method, resulting in higher costs. In addition, in the double shielded TIG welding method, welding may be performed by passing a pulsed welding current.

[0005] Therefore, an object of the present invention is to provide a double-shielded TIG welding method capable of reducing the amount of gas consumption when welding is performed by passing a pulsed welding current. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, the invention of claim 1 comprises: A welding torch having an inner nozzle for ejecting an inner gas and an outer nozzle for ejecting an outer gas is used, In a double shield TIG welding method, a welding current having a pulse waveform formed by a peak current during a peak period and a base current during a base period is applied to perform welding, The inner gas is ejected during the peak period, The ejection of the inner gas is stopped during the base period. This is a double shielded TIG welding method characterized by the above.

[0007] The invention of claim 2 is as follows: The flow rate of the inner gas is increased as the value of the peak current increases. 2. The double shielded TIG welding method according to claim 1,

[0008] The invention of claim 3 is as follows: When the frequency of the pulse waveform is equal to or greater than the reference frequency, The flow rate of the inner gas during the peak period is decreased as the frequency increases. 3. The double shield TIG welding method according to claim 1 or 2. Effect of the Invention

[0009] According to the double shielded TIG welding method of the present invention, when welding is performed by passing a pulsed welding current, it is possible to reduce the amount of gas consumed. [Brief description of the drawings]

[0010] [Figure 1] 1 is a block diagram of a welding apparatus for carrying out a double-shielded TIG welding method according to an embodiment of the present invention. [Diagram 2] 2 is a timing chart of each signal in the welding apparatus of FIG. 1 illustrating a double-shielded TIG welding method according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0012] 1 is a block diagram of a welding apparatus for carrying out a double shielded TIG welding method according to an embodiment of the present invention. Each block will be described below with reference to the diagram.

[0013] The welding torch WT mainly includes an electrode 1, an inner nozzle 4 surrounding the electrode 1, and an outer nozzle 5 surrounding the inner nozzle 4. A tungsten electrode or the like is used for the electrode 1. For example, the inner diameter of the inner nozzle 4 is 5 mm, and the inner diameter of the outer nozzle 5 is 13 mm.

[0014] The start switch ON outputs a start signal On that goes to a high level when it is turned on and goes to a low level when it is turned off. This start switch ON is a torch switch provided on the welding torch WT. The start signal On may also be output from the robot control device.

[0015] The peak period setting circuit TPR outputs a predetermined peak period setting signal Tpr, and the base period setting circuit TBR outputs a predetermined base period setting signal Tbr.

[0016] The pulse frequency setting circuit PFR receives the peak period setting signal Tpr and the base period setting signal Tbr, calculates a frequency from both values, and outputs the pulse frequency setting signal Pfr. For example, when Tpr=0.25 seconds and Tbr=0.25 seconds, Fr=1 / (0.25+0.25)=2Hz. The setting range of the frequency setting signal Fr is 0.2 to 500Hz.

[0017] The peak current setting circuit IPR outputs a predetermined peak current setting signal Ipr, and the base current setting circuit IBR outputs a predetermined base current setting signal Ibr.

[0018] The current setting circuit IR receives the peak period setting signal Tpr, the base period setting signal Tbr, the peak current setting signal Ipr, and the base current setting signal Ibr as inputs, and repeats the following processes 1) and 2) to output a current setting signal Ir and a peak period signal Stp. 1) During the peak period Tp set by the peak period setting signal Tpr, the peak current setting signal Ipr is output as the current setting signal Ir, and the peak period signal Stp is output at a High level. 2) Subsequently, during the base period Tb set by the base period setting signal Tbr, the base current setting signal Ibr is output as the current setting signal Ir, and the peak period signal Stp is output at a Low level.

[0019] The inner gas flow rate setting circuit FIR receives the peak current setting signal Ipr, the pulse frequency setting signal Pfr, and the peak period signal Stp as inputs, performs the following processes 1) and 2), and outputs an inner gas flow rate setting signal Fir. 1) When the peak period signal Stp is at a high level (peak period Tp), the peak current setting signal Ipr [A] and the pulse frequency setting signal Pfr [Hz] are input into a predetermined inner gas flow rate setting function, and the calculated value is output as the inner gas flow rate setting signal Fir [l / min]. 2) When the peak period signal Stp is at a low level (base period Tb), the inner gas flow rate setting signal Fir=0 is output. As a result, the inner gas is ejected during the peak period Tp, and the ejection of the inner gas is stopped during the base period Tb. An example of an inner gas setting function is shown below. Fir=(Ipr-75) / 50+3.5-K×Pfr (1) formula However, the range is 75≦Ipr≦150, and when Ipr<75, the value is the same as Ipr=75, and when Ipr>150, the value is the same as Ipr=150. As a result, the value of the inner gas flow rate setting signal Fir increases as the value of the peak current setting signal Ipr increases. Furthermore, the constant K is 0 when Pfr<reference frequency, and 0.015 when Pfr≧reference frequency. The reference frequency is, for example, 10 Hz. The range is 0.2≦Pfr≦500, and when Pfr>100, the value is the same as Pfr=100. As a result, when the value of the pulse frequency setting signal Pfr is equal to or higher than the reference frequency, the value of the inner gas flow rate setting signal Fir during the peak period Tp decreases as the value of the pulse frequency setting signal Pfr increases.

[0020] The inner gas flow regulator CI is a commonly used mass flow controller that receives the above-mentioned start signal On and the above-mentioned inner gas flow setting signal Fir as inputs, and when the start signal On becomes high level, it adjusts the flow rate Fi of the inner gas 7 from the inner gas cylinder 6 to a value determined by the inner gas flow setting signal Fir and sprays it.

[0021] The outer gas flow rate setting circuit FOR receives the peak current setting signal Ipr as an input, inputs the peak current setting signal Ipr [A] to a predetermined outer gas flow rate setting function, and outputs the calculated value as the outer gas flow rate setting signal For [l / min]. An example of the outer gas flow rate setting function is shown below. For=(Ipr-75) / 50+5.5 (2) Formula However, the range is 75≦Ipr≦150, and when Ipr<75, the value is the same as Ipr=75, and when Ipr>150, the value is the same as Ipr=150.

[0022] The outer gas flow regulator CO is a commonly used mass flow controller that receives the above-mentioned start signal On and the above-mentioned outer gas flow setting signal For as inputs. When the start signal On becomes high level, it adjusts the flow rate Fo of the outer gas 9 from the outer gas cylinder 8 to a value determined by the outer gas flow setting signal For and sprays it.

[0023] An inner gas 7 flows through a passage inside the inner nozzle 4. An outer gas 9 flows through a passage outside the inner nozzle 4 and inside the outer nozzle 5. An inert gas such as argon or helium is used as the inner gas 7 and the outer gas 9. The arc 3 is generated with the electrode 1 serving as the negative electrode and the base material 2 serving as the positive electrode.

[0024] The welding power source PS receives as input the above-mentioned start signal On and the above-mentioned current setting signal Ir, and when the start signal On goes to high level, it applies a high frequency high voltage between the electrode 1 and the base material 2, and when an arc 3 is generated, it begins outputting the welding current Iw having a pulse waveform set by the current setting signal Ir, and when the start signal On goes to low level, it stops outputting the welding current Iw.

[0025] Fig. 2 is a timing chart of each signal in the welding device of Fig. 1, which shows the double-shielded TIG welding method according to the embodiment of the present invention. Fig. 2(A) shows the time change of the welding current Iw [A], Fig. 2(B) shows the time change of the inner gas flow rate Fi [l / min], and Fig. 2(C) shows the time change of the outer gas flow rate Fo [l / min]. The operation during welding will be described below with reference to the figures.

[0026] As shown in FIG. 1A, the welding current Iw has a pulse waveform of a substantially rectangular wave, and a peak current Ip flows during a peak period Tp from time t1 to t2, and a base current Ib flows during a base period Tb from time t2 to t3. The peak period Tp is set by the peak period setting signal Tpr in FIG. 1, the peak current Ip is set by the peak current setting signal Ipr in FIG. 1, the base period Tb is set by the base period setting signal Tbr in FIG. 1, and the base current Ib is set by the base current setting signal Ibr in FIG. 1. The pulse frequency is calculated by 1 / (Tp+Tb), where Ip>Ib. The current amplitude is Ip-Ib, and is 50A or more. The pulse frequency is in the range of 0.2 to 500Hz.

[0027] As shown in FIG. 1C, the outer gas flow rate Fo is a value calculated by substituting the peak current setting signal Ipr in FIG. 1 into the above-mentioned formula (2). The outer gas flow rate Fo is the same value for both the peak period Tp and the base period Tb. The outer gas is ejected to shield the arc from the atmosphere. For this reason, the outer gas flow rate Fo is set to a value that can shield the arc passing through the peak current Ip. For example, when the peak current Ip is 150A, Fo=7 l / min.

[0028] As shown in FIG. 1B, the inner gas flow rate Fi is a value calculated by substituting the peak current setting signal Ipr and the pulse frequency setting signal Pfr of FIG. 1 into the above-mentioned formula (1) during the peak period Tp from time t1 to t2. On the other hand, the inner gas flow rate Fi is 0 during the base period Tb from time t2 to t3 because the inner gas flow rate setting signal Fir=0 of FIG. 1. The inner gas flow rate Fi increases from the value 0 at time t1 to the value at the peak period Tp with a slope, and decreases from the value at the peak period Tp at time t2 with a slope to 0. Therefore, the inner gas is ejected during the peak period Tp, and the ejection of the inner gas is stopped during the base period Tb. The rigidity of the arc can be strengthened by ejecting the inner gas. As a result, the welding speed can be increased and the penetration can be deepened. The rigidity of the arc is strengthened by ejecting the inner gas during the peak period Tp. On the other hand, since the base current Ib is a small current value during the base period Tb, the rigidity of the arc is hardly strengthened even if the inner gas is ejected. For this reason, in this embodiment, the inner gas is ejected during the peak period Tp and the ejection is stopped during the base period Tb, thereby reducing the consumption of the inner gas.

[0029] Furthermore, it is preferable to increase the inner gas flow rate Fi as the value of the peak current Ip increases. In formula (1), when Ip=100A, Fi=4.5 l / min, and when Ip=150A, Fi increases to 5 l / min. The larger the value of the peak current Ip, the larger the arc spread. Therefore, in order to strengthen the rigidity of the arc, it is preferable to increase the inner gas flow rate Fi in proportion to the value of the peak current Ip.

[0030] Furthermore, when the pulse frequency is equal to or higher than the reference frequency, it is preferable to reduce the inner gas flow rate Fi during the peak period Tp as the pulse frequency increases. The reference frequency is, for example, 10 Hz. The higher the pulse frequency is compared to the reference frequency, the stronger the rigidity of the arc becomes. Also, the larger the inner gas flow rate Fi, the stronger the rigidity of the arc becomes. For this reason, when the pulse frequency is changed to be higher than the reference frequency, if the inner gas flow rate Fi is left unchanged and is kept at the same value, the shape of the arc may be too narrowed, causing the welding state to become unstable. In contrast, in this embodiment, the inner gas flow rate Fi becomes smaller as the pulse frequency becomes higher than the reference frequency, so that the shape of the arc is prevented from being too narrowed, and the welding state can be maintained stably. In the above formula (1), when Ip=150A and the pulse frequency is less than the reference frequency of 10Hz, Fi=5l / min. When the pulse frequency=20Hz, Fi decreases to 5-0.3=4.7l / min. When the pulse frequency=100Hz, Fi decreases to 5-1.5=3.5l / min. [Explanation of symbols]

[0031] 1 electrode 2 Base material 3. Arc 4 Inner nozzle 5 Outer nozzle 6 Inner gas cylinder 7. Inner Gas 8 Outer gas cylinder 9. Outer Gas CI Inner Gas Flow Regulator CO outer gas flow regulator Fi Inner gas flow rate FIR inner gas flow rate setting circuit Fir inner gas flow rate setting signal Fo Outer gas flow rate FOR OUTER GAS FLOW SETTING CIRCUIT For outer gas flow rate setting signal Ib Base current IBR base current setting circuit Ibr Base current setting signal Ip Peak current IPR Peak current setting circuit Ipr Peak current setting signal IR current setting circuit Ir Current setting signal Iw Welding current ON Start switch On Start signal PFR Pulse frequency setting circuit Pfr Pulse frequency setting signal PS Welding Power Source Tb Base period TBR Base period setting circuit Tbr Base period setting signal Tp peak period TPR peak period setting circuit Tpr Peak period setting signal WT Welding Torch

Claims

1. A welding torch having an inner nozzle for ejecting an inner gas and an outer nozzle for ejecting an outer gas is used, 1. A double shielded TIG welding method for welding by passing a welding current having a pulse waveform formed by a peak current during a peak period and a base current during a base period, The inner gas is ejected during the peak period, The ejection of the inner gas is stopped during the base period. A double shielded TIG welding method.

2. The flow rate of the inner gas is increased as the value of the peak current increases. The double shielded TIG welding method according to claim 1 .

3. When the frequency of the pulse waveform is equal to or greater than the reference frequency, The flow rate of the inner gas during the peak period is decreased as the frequency increases.

3. The double shielded TIG welding method according to claim 1 or 2.

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