Arc welding equipment

Abstract

To make it relatively easy to adjust the arc spread. [Solution] A preset welding current is defined as the set current Iv, and a predetermined ratio of the amplitude in the waveform of the welding current is defined as the amplitude ratio d. A welding current that is greater than the set current Iv at amplitude ratio d is defined as the peak current Ip, and a welding current that is less than the set current Iv at amplitude ratio d is defined as the base current Ib. The welding control unit 22 controls the operation of the welding power supply 20 so as to switch the welding current between the peak current Ip and the base current Ib based on a predetermined frequency.

Description

Technical Field

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[0001] The present invention relates to an arc welding apparatus.

Background Art

[0002] Patent Document 1 discloses a DC TIG welding machine having a DC voltage source and a switching element, which supplies a voltage to a welded portion by opening and closing the switching element and performs a high-frequency start at the start of welding. <00000l0>

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in a conventional DC TIG welding machine, for example, a gap occurs during butt welding of a workpiece, and even when it is desired to widen the bead width, the arc cannot be easily widened, and there is a risk of melting of the workpiece. Therefore, there has been a demand for adjusting the spread of the arc according to the required bead width.

[0005] The present invention has been made in view of such points, and an object thereof is to enable adjustment of the spread of the arc relatively easily.

Means for Solving the Problems

[0006] The first invention is an arc welding apparatus for welding a consumable filler material by melting it with an arc generated between a non-consumable electrode and a workpiece, comprising: a welding power supply that supplies welding output to the electrode; and a welding control unit that controls the waveform of the welding current flowing through the electrode, wherein the set welding current is defined as the set current Iv, the amplitude ratio d is defined as a predetermined ratio of amplitude in the waveform of the welding current, the peak current Ip is defined as the welding current that is greater than the set current Iv at the amplitude ratio d, and the base current Ib is defined as the welding current that is less than the set current Iv at the amplitude ratio d, and the welding control unit controls the operation of the welding power supply so as to switch the welding current between the peak current Ip and the base current Ib based on a predetermined frequency.

[0007] In the first invention, by repeatedly performing actions to widen the arc by bringing the welding current closer to the peak current and to narrow the arc by bringing the welding current closer to the base current, it is possible to reduce the heat input to the workpiece while ensuring the required bead width.

[0008] In this way, by adjusting the amplitude ratio and frequency, the arc's spread and concentration can be controlled, thereby reducing the workpiece's melting speed and preventing it from melting too rapidly.

[0009] The second invention relates to the arc welding apparatus of the first invention, wherein the peak current Ip satisfies the condition Ip = (1 + d) × Iv, and the base current Ib satisfies the condition Ib = (1 - d) × Iv.

[0010] In the second invention, the peak current and base current can be set based on a predetermined amplitude ratio. This allows the arc spread to be adjusted according to the required bead width and the gap during butt welding of workpieces.

[0011] The third invention is an arc welding apparatus according to the first or second invention, wherein the frequency is 70 Hz or higher and 120 Hz or lower.

[0012] In the third invention, when switching the welding current value at a predetermined frequency, it is possible to suppress arc flicker caused by a frequency that is too low. In addition, it is possible to suppress the deterioration of arc visibility caused by a frequency that is too high. [Effects of the Invention]

[0013] According to the present invention, the arc spread can be adjusted relatively easily. [Brief explanation of the drawing]

[0014] [Figure 1] This is a schematic diagram of the arc welding apparatus according to this embodiment. [Figure 2] This graph shows the relationship between elapsed time and welding current during arc welding, as a comparative example. [Figure 3] This graph shows the relationship between elapsed time and welding current during arc welding. [Figure 4] This figure shows the relationship between amplitude ratio and frequency. [Figure 5] This diagram shows a magnified view of a portion of the triangular waveform current command in a graph illustrating the relationship between elapsed time and welding current during arc welding. [Modes for carrying out the invention]

[0015] Embodiments of the present invention will be described below with reference to the drawings. The following description of preferred embodiments is essentially illustrative and is not intended to limit the present invention, its applications, or its uses.

[0016] As shown in Figure 1, the arc welding apparatus 1 comprises a welding torch 10 and a welding power source 20. The arc welding apparatus 1 constitutes a DC TIG welding apparatus.

[0017] The welding torch 10 comprises a torch body 11 and an electrode 12. The torch body 11 holds the electrode 12. The electrode 12 is made of a non-consumable electrode.

[0018] The welding power source 20 is connected to the welding torch 10 and the work W. The welding power source 20 supplies a welding output between the electrode 12 and the work W, thereby generating an arc 13 between the electrode 12 and the work W. The consumable filler metal 15 is supplied toward the work W. The filler metal 15 is melted by the arc 13. Thereby, the work W is arc welded.

[0019] The welding power source 20 includes a welding output unit 21, a welding control unit 22, a current detection unit 23, a voltage detection unit 24, and a setting unit 26.

[0020] A three-phase AC power source PS is connected to the welding output unit 21. The welding output unit 21 rectifies the AC power received from the three-phase AC power source PS and converts it into a welding output by an inverter circuit or the like. The welding output unit 21 outputs the welding output. Specifically, the welding output unit 21 outputs a welding voltage and a welding current suitable for welding in the positive polarity direction (when the electrode 12 is negative and the work W is positive). Thereby, a welding voltage is applied between the electrode 12 and the work W, and a welding current flows through the electrode 12 and the work W.

[0021] The welding control unit 22 controls the operation of the welding output unit 21. As will be described later, the welding control unit 22 controls the waveform of the welding current flowing through the electrode 12.

[0022] The current detection unit 23 detects the welding current. The voltage detection unit 24 detects the welding voltage.

[0023] The setting unit 26 sets welding conditions such as a set current Iv, an amplitude ratio d, a frequency f, etc., which will be described later, in conjunction with the parameters input by the operator. The setting unit 26 outputs the set value to the welding control unit 22.

[0024] Various set values set by the setting unit 26, a voltage detection signal detected by the voltage detection unit 24, and a current detection signal detected by the current detection unit 23 are input to the welding control unit 22. The welding control unit 22 outputs an output command signal for commanding the welding output to the welding output unit 21.

[0025] <Adjusting the arc spread> By the way, in the arc welding apparatus 1, as shown in the comparative example in Figure 2, the welding current is controlled so that the preset welding current Iv remains constant. In the example shown in Figure 2, since the preset current Iv is constant during the arc welding period, the arc spread 13 also remains constant.

[0026] However, if the arc 13 is controlled to spread at a constant rate, for example, when a gap occurs during butt welding of workpieces W and it is desired to widen the bead width, it is not possible to easily widen the arc 13, and there is a risk of burn-through of the workpiece W. Therefore, there was a request to be able to adjust the arc 13's spread according to the required bead width.

[0027] Therefore, in this embodiment, the arc 13 can be adjusted relatively easily.

[0028] Specifically, as shown in Figure 3, the preset welding current is defined as the set current Iv [A], the amplitude ratio d is defined as a predetermined ratio of amplitude in the waveform of the welding current, the welding current that is greater than the set current Iv at amplitude ratio d is defined as the peak current Ip [A], and the welding current that is less than the set current Iv at amplitude ratio d is defined as the base current Ib [A].

[0029] As will be explained in more detail later, the amplitude ratio d here is the absolute value representing the ratio of the peak current Ip to the set current Iv, or the ratio of the base current Ib to the set current Iv.

[0030] The welding control unit 22 controls the operation of the welding output unit 21 in the welding power supply 20 so as to switch the welding current between a peak current Ip and a base current Ib based on a predetermined frequency f [Hz]. Specifically, the welding current is changed so that the waveform of the welding current becomes a triangular waveform. Alternatively, the welding current may be changed so that the waveform becomes a sine wave.

[0031] In this way, by making the welding current waveform a triangular waveform, the slope of the pulse rise can be made gentler compared to the conventional rectangular or trapezoidal waveforms. This makes it possible to adjust the spread of the arc 13 and optimize the heat input range while suppressing the noise caused by the generation of the arc 13.

[0032] Furthermore, by repeatedly widening the arc 13 by bringing the welding current closer to the peak current Ip, and narrowing the arc 13 by bringing the welding current closer to the base current Ib, it is possible to reduce the heat input to the workpiece W while ensuring the required bead width.

[0033] Furthermore, by adjusting the amplitude ratio d and frequency f, the degree of arc spread and concentration of the arc 13 can be controlled, thereby reducing the melting speed of the workpiece W and preventing the workpiece W from melting too rapidly.

[0034] In this embodiment, the peak current Ip is set to satisfy the condition Ip = (1 + d) × Iv. The base current Ib is also set to satisfy the condition Ib = (1 - d) × Iv.

[0035] The amplitude ratio d can be set within the range of 0.01 ≤ d ≤ 0.99. Here, the amplitude ratio d is, in other words, the absolute value representing the ratio of the peak current Ip to the set current Iv, or the ratio of the base current Ib to the set current Iv.

[0036] For example, when the amplitude ratio d is 0.5, the peak current Ip will be 1.5 times the set current Iv. The base current Ib will be 0.5 times the set current Iv. The larger the amplitude ratio d, the more the arc 13 tends to spread.

[0037] In this way, the peak current Ip and base current Ib can be set based on a predetermined amplitude ratio d. This allows the arc 13 to be adjusted while suppressing heat input, according to the required bead width and the gap during butt welding of the workpiece W. Furthermore, the arc 13 can be adjusted with a soft arc feel, reducing the burden on the operator.

[0038] Here, it is preferable to set the frequency f within the range of 50 Hz or higher and 200 Hz or lower. Specifically, if the frequency f is less than 50 Hz, the afterimage of the arc 13 will not be visible intermittently but will appear to flicker, thus worsening the workability of arc welding.

[0039] On the other hand, when the frequency f exceeds 200 Hz, the afterimage of the arc 13 becomes difficult to see, and the spread of the arc 13 becomes harder to discern. Furthermore, the noise associated with the generation of the arc 13 increases, increasing the burden on the worker.

[0040] As will be explained in more detail later, it is preferable to set the frequency f to be between 70Hz and 120Hz.

[0041] In this embodiment, for example, the peak current Ip is set to Ip < 200, the base current Ib is set to Ib > 5, and the frequency f is set to f = 80.

[0042] Figure 4 shows the relationship between amplitude ratio and frequency. In the example shown in Figure 4, the amplitude ratio d is varied by 0.1 increments from 0.1 to 0.9. Also, the frequency f is varied by 10 Hz increments from 50 Hz to 160 Hz.

[0043] In Figure 4, the triangle ("△") indicates a state where the arc 13 is discontinuous in its spread and its visibility is uneven. Because the arc 13 flickers, it is difficult to align the workpiece W and filler material 15 with the arc 13, resulting in poor workability. In addition, the heat input range becomes narrower or uneven.

[0044] In Figure 4, "○" indicates a state where the arc 13 spreads naturally and its spread is visible. The behavior of the arc 13 is nearly uniform and easy to work with. In addition, the heat input area is widened, and the heat input per unit area decreases.

[0045] In Figure 4, "◎" indicates a state where the continuity of arc 13 appears more naturally smooth and the expansion of arc 13 is more naturally visible compared to the state marked "○". The behavior of arc 13 is less flickering, slightly larger than the width of the weld bead, and more uniform and stable, making it easier to work with. In addition, the heat input range is wider and the heat input per unit area is lower.

[0046] In the example shown in Figure 4, the state is marked with a "○" when the amplitude ratio d is 0.4 and the frequency f is between 70 Hz and 150 Hz. Therefore, the spread of the arc 13 can be easily visualized, and the behavior of the arc 13 is nearly uniform and easy to work with. In addition, the heat input range is widened, and the heat input per unit area decreases.

[0047] On the other hand, when the frequency f is less than 70Hz, the condition becomes "△", causing the arc 13 to appear discontinuous and flickering, making installation difficult. Also, when the frequency f is greater than 150Hz, the arc 13 tends to narrow, making it difficult to visually observe the spread of the arc 13.

[0048] Next, in the range where the amplitude ratio d is 0.5 and the frequency f is between 60Hz and 140Hz, the condition is "○" or "◎". Therefore, the spread of arc 13 can be naturally observed, and the behavior of arc 13 is almost uniform and easy to work with.

[0049] On the other hand, when the frequency f is less than 60Hz, the condition becomes "△", causing the arc 13 to appear discontinuous and flickering, making construction difficult. Also, when the frequency f is greater than 140Hz, the arc 13 tends to narrow, making it difficult to visually perceive the spread of the arc 13.

[0050] Here, the condition is marked "◎" when the amplitude ratio d is 0.5 and the frequency f is between 80Hz and 100Hz. As a result, the continuity of arc 13 appears more natural and smoother, making it easier to install.

[0051] In this case, the arc 13 spreads slightly wider than the width of the bead, resulting in continuous arc emission. Furthermore, the heat input area widens, and this continuous expansion averages out the heat input area, leading to more stable heat input per unit area. This makes it possible to suppress melt-through of the workpiece W when the workpiece W has a gap or when the workpiece W is thin (e.g., 1.5 mm or less).

[0052] Next, in the range where the amplitude ratio d is 0.6 or more and 0.9 or less, and the frequency f is 60 Hz or more and 140 Hz or less, the condition is "○" or "◎". Therefore, the spread of the arc 13 can be naturally observed, and the behavior of the arc 13 is almost uniform and easy to work with.

[0053] On the other hand, when the frequency f is less than 60Hz, the condition becomes "△", causing the arc 13 to appear discontinuous and flickering, making installation difficult. Also, when the frequency f is greater than 140Hz, the arc 13 tends to narrow, making it difficult to visually perceive the spread of the arc 13.

[0054] Here, the condition is marked "◎" when the amplitude ratio d is between 0.6 and 0.9, and the frequency f is between 80Hz and 110Hz. As a result, the continuity of arc 13 appears more naturally smooth and easier to work with.

[0055] In this case, the arc 13 spreads slightly wider than the width of the bead, resulting in continuous arc emission. Furthermore, the heat input area widens, and this continuous expansion averages out the heat input area, leading to more stable heat input per unit area. This makes it possible to suppress melt-through of the workpiece W when the workpiece W has a gap or when the workpiece W is thin (e.g., 1.5 mm or less).

[0056] As described above, the spread and concentration of the arc 13 can be controlled by adjusting the amplitude ratio d and frequency f.

[0057] Specifically, the adjustment of arc 13 involves roughly adjusting the spread of arc 13 using the amplitude ratio d, and fine-tuning the degree of arc 13's spread using the frequency f.

[0058] As the amplitude ratio d increases, the arc 13 tends to widen. As the amplitude ratio d decreases, the arc 13 tends to narrow. Also, as the frequency f decreases, the arc 13 tends to widen. As the frequency f increases, the arc 13 tends to narrow. Therefore, the frequency f should be set according to the desired widening of the arc 13.

[0059] Here, if the frequency f is too low, the arc 13 will not appear continuous and will flicker, resulting in poor workability. Conversely, if the frequency f is too high, the light emission of the arc 13 itself will be difficult to see, and the arc 13 will narrow. Note that adjusting the amplitude ratio d has little effect on the flickering of the arc 13 or the visibility of the light emission of the arc 13 itself.

[0060] Based on the above considerations, in this embodiment, the frequency f is set to be between 70 Hz and 120 Hz.

[0061] This makes it possible to suppress arc flickering caused by a frequency f that is too low when switching the welding current value at a predetermined frequency f. It also makes it possible to suppress the deterioration of arc visibility caused by a frequency f that is too high.

[0062] In this embodiment, we have described a configuration in which the welding current is changed so that the waveform of the welding current becomes a triangular waveform. More specifically, as shown in Figure 5, the waveform is a triangular waveform that includes ripple.

[0063] Specifically, when switching the welding current between the peak current Ip and the base current Ib based on a predetermined frequency f, the current command from the peak current Ip to the base current Ib does not change linearly, but rather changes in a zigzag pattern along a linear current command. The same applies to the current command from the base current Ib to the peak current Ip.

[0064] In this embodiment, the arc welding apparatus 1 is configured as a DC TIG welding apparatus. This is because, in the case of AC welding, the EP (electrode positive) side current flows, and due to the cleaning action (removal of the oxide film from the filler material 15), arc discharge occurs from the remaining oxide film, making the arc 13 itself unstable. [Industrial applicability]

[0065] As described above, the present invention is extremely useful and has high industrial applicability because it provides the highly practical effect of being able to adjust the arc spread relatively easily. [Explanation of Symbols]

[0066] 1. Arc welding equipment 12 electrodes 13 Arc 15 Filler metal 20 Welding power supply 22 Welding Control Unit d Amplitude ratio f frequency Ib Base current Ip Peak Current IV setting current Double job

Claims

1. An arc welding apparatus that performs welding by melting a consumable filler material with an arc generated between a non-consumable electrode and a workpiece, A welding power supply that supplies welding output to the electrode, The system includes a welding control unit that controls the waveform of the welding current flowing through the electrode, The pre-set welding current is defined as the set current Iv, the amplitude ratio d is defined as a predetermined ratio of the amplitude in the waveform of the welding current, the welding current that is greater than the set current Iv at the amplitude ratio d is defined as the peak current Ip, and the welding current that is less than the set current Iv at the amplitude ratio d is defined as the base current Ib. The welding control unit controls the operation of the welding power supply so as to switch the welding current between the peak current Ip and the base current Ib based on a predetermined frequency. Arc welding equipment.

2. In the arc welding apparatus according to claim 1, The aforementioned peak current Ip satisfies the condition Ip = (1 + d) × Iv, The base current Ib satisfies the condition Ib = (1 - d) × Iv Arc welding equipment.

3. In the arc welding apparatus according to claim 1 or 2, The aforementioned frequency is 70 Hz or higher and 120 Hz or lower. Arc welding equipment.

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