Method for setting welding condition of submerged arc welding

Abstract

To improve efficiency of test welding for setting welding conditions in submerged arc welding.SOLUTION: A method for setting welding conditions in submerged arc welding is provided in which welding is performed by supplying a welding voltage Vw and a welding current Iw while moving a distal end of a welding torch 4 along a welding line, the method includes a welding mode Ms having a test welding mode and an actual production welding mode. In the test welding mode, a plurality of sections are set along a welding line, and when the distal end position of the welding torch 4 moves within each section, welding conditions Vr and Ir are adjusted. When the distal end position of the welding torch 4 reaches an end position of each section, the welding conditions Vr and Ir at that moment are stored for each section and test welding is performed. In the actual production welding mode, one of the welding conditions Vr and Ir stored for each section is selected based on the welding result, and actual production welding is performed.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for setting welding conditions for submerged arc welding. [Background technology]

[0002] Submerged arc welding has been known for some time. In submerged arc welding, granular flux is scattered on a base metal, a welding wire is fed into the flux, and an arc is generated between the tip of the welding wire and the base metal to perform welding. In submerged arc welding, a large current is passed through a large-diameter welding wire, allowing thick plates to be welded with high efficiency (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 9-271944 Summary of the Invention [Problem to be solved by the invention]

[0004] In submerged arc welding, the welding preparation is time-consuming because a groove must be prepared in the thick plate. Furthermore, in submerged arc welding, the arc generation part is covered with flux, so the welding state cannot be directly observed. Therefore, it is not possible to determine whether the welding conditions are appropriate unless the appearance of the bead is checked after welding is completed. For this reason, there is a problem with submerged arc welding in that test welding to set the welding conditions is time-consuming.

[0005] Therefore, an object of the present invention is to provide a method for setting welding conditions for submerged arc welding, which can, for example, improve the efficiency of test welding for setting welding conditions. [Means for solving the problem]

[0006] A first aspect of the present invention provides a method for setting welding conditions for submerged arc welding, in which a welding voltage and a welding current are applied while the tip position of a welding torch is moved along a welding line, and the method includes a test welding mode and an actual construction welding mode. In the test welding mode, a plurality of sections are set along the welding line, and welding conditions are adjusted as the tip position of the welding torch moves through each section. When the tip position of the welding torch reaches an end position of each section, the welding conditions at that time are stored for each section and test welding is performed. In the actual construction welding mode, one of the welding conditions stored for each section is selected based on the welding result and actual construction welding is performed.

[0007] As an example, the method for setting welding conditions for submerged arc welding according to the present invention is characterized in that the welding conditions include setting conditions for at least the welding voltage and the welding current.

[0008] As an example, the method for setting welding conditions for submerged arc welding of the present invention is characterized in that, in the test welding mode, when the tip position of the welding torch reaches the start position of each section, a notification to that effect is issued, and when the tip position of the welding torch is moving within each section, the welding operator manually adjusts the welding conditions.

[0009] As an example, the method for setting welding conditions for submerged arc welding according to the present invention is characterized in that each of the sections is set based on the elapsed time from the start of welding.

[0010] As an example, the method for setting welding conditions for submerged arc welding of the present invention is characterized in that, when the test welding is being performed for each section, an evaluation index for the welding state is calculated based on at least the welding voltage and stored for each section, and when the actual welding mode is being performed, the welding conditions are selected based on the evaluation index. [Effects of the Invention]

[0011] According to the above configuration, for example, in relation to the method for setting welding conditions for submerged arc welding, it is possible to improve the efficiency of test welding for setting welding conditions. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a block diagram of a welding device for carrying out a method for setting welding conditions for submerged arc welding according to an embodiment of the present invention. [Figure 2] 2 is a timing chart of each signal in the welding device of FIG. 1, illustrating a method for setting welding conditions for submerged arc welding according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0014] 1 is a block diagram of a welding device for carrying out a method for setting welding conditions for submerged arc welding according to an embodiment of the present invention. Each block will be described below with reference to the diagram.

[0015] The welding mode selection circuit MS is provided on the front panel of the welding power source PS and is a circuit that allows the welding operator to switch between test welding mode and actual construction welding mode. It outputs a welding mode signal Ms that goes to a high level when test welding mode is selected and to a low level when actual construction welding mode is selected.

[0016] The welding voltage setting circuit VR is provided on the front panel of the welding power source PS or the like, and outputs a welding voltage setting signal Vr that is manually adjusted by the welding operator. The welding current setting circuit IR is provided on the front panel of the welding power source PS or the like, and outputs a welding current setting signal Ir that is manually adjusted by the welding operator.

[0017] The welding start circuit ST is a push button or the like, and outputs a welding start signal St that goes to a high level when turned on by a welding operator.

[0018] The energization determination circuit CD outputs an energization determination signal Cd that goes high when it determines that the welding current Iw is being applied.

[0019] The section elapsed time setting circuit TSR is a touch panel or the like provided on the front panel of the welding power source PS, and outputs a section elapsed time setting signal Tsr adjusted by the welding operator. The welding operator operates the touch panel to set the section elapsed time setting signal Tsr to 1 minute, 2 minutes, etc.

[0020] The section setting circuit SR receives the energization determination signal Cd and the section elapsed time setting signal Tsr as inputs. When the energization determination signal Cd is at a low level, the section setting signal Sr=0 is output. When the energization determination signal Cd changes to a high level, the section setting signal Sr=1 is output. Thereafter, the section setting circuit SR counts up and outputs the section setting signal Sr each time the time set by the section elapsed time setting signal Tsr elapses. For example, if the time elapsed from the start of welding to the end of welding is five minutes and the section elapsed time is one minute, Sr=1 is output when the energization determination signal Cd changes to a high level. Then, Sr counts up to 2, 3, 4, and 5 each time one minute elapses, and reaches Sr=0 when five minutes have elapsed. That is, the weld line is formed from sections 1 to 5, with Sr=1 being section 1 and Sr=5 being section 5.

[0021] The welding voltage detection circuit VD detects the welding voltage Vw and outputs a welding voltage detection signal Vd.

[0022] The welding condition memory circuit WM receives the above-mentioned welding mode signal Ms, the above-mentioned section setting signal Sr, the above-mentioned welding voltage setting signal Vr, the above-mentioned welding current setting signal Ir, and the above-mentioned welding voltage detection signal Vd as inputs, and when the welding mode signal Ms is at a high level, which indicates the test welding mode, performs the following processing and stores the values ​​of the welding voltage setting signal Vr, the welding current setting signal Ir, and the welding state evaluation index signal Wc in combination with the section setting signal Sr as the welding condition memory signal Wm. 1) When the section setting signal Sr is counted up, the fact is notified by sound, light, display on the display, etc. 2) During each interval, the welding operator adjusts the welding voltage setting signal Vr and the welding current setting signal Ir. 3) The welding condition in each section is evaluated based on the welding voltage detection signal Vd from its fluctuation, occurrence of short circuit, occurrence of arc interruption, etc., to calculate the welding condition evaluation index signal Wc. 4) When the section setting signal Sr changes, the values ​​of the welding voltage setting signal Vr, the welding current setting signal Ir, and the welding condition evaluation index signal Wc at that time are stored in combination with the section setting signal Sr of the previous section. For example, when Sr is counted up from 1 to 2, a notification is issued to that effect, and when Sr is counted up to 3, the values ​​of Vr, Ir, and Wc at that time are stored in combination with Sr=2.

[0023] The welding condition setting circuit WR receives the welding mode signal Ms and the welding condition memory signal Wm as inputs, and when the welding mode signal Ms is at a low level (practical welding mode), when the welding operator selects one section from a plurality of sections based on the welding result such as the bead appearance and the welding state evaluation index signal Wc included in the welding condition memory signal Wm, outputs the welding voltage setting value stored in the welding condition memory signal Wm corresponding to the selected section as the welding voltage setting signal Vr and outputs the welding current setting value as the welding current setting signal Ir.

[0024] The welding power source PS receives the welding start signal St, the welding voltage setting signal Vr, and the welding current setting signal Ir as inputs. When the welding start signal St goes high, the welding power source PS receives a commercial AC power supply (not shown), such as a three-phase 200V power supply, as input, and performs output control such as inverter control based on the welding voltage setting signal Vr to output the welding voltage Vw and the welding current Iw, and outputs a feed control signal Fc to the wire feeder WF based on the welding current setting signal Ir. Since the welding power source PS is under constant voltage control, the welding voltage Vw is controlled to the value of the welding voltage setting signal Vr. The welding power source PS may also be under constant current control. The welding voltage Vw and the welding current Iw may be DC or AC.

[0025] The feeder WF is equipped with a feed motor, and receives the above-mentioned feed control signal Fc as an input to feed the welding wire 1 through the welding torch 4 to the base material 2. The feed speed of the welding wire 1 corresponds to the value of the welding current setting signal Ir.

[0026] Welding torch 4 guides welding wire 1 to base material 2 and supplies power to welding wire 1 via a power feed tip (not shown).

[0027] The flux spreader 5 spreads flux onto the weld line.

[0028] The automatic carriage AT receives the energization discrimination signal Cd as an input and is equipped with the welding torch 4 and the flux spreader 5. When the energization discrimination signal Cd changes to a high level, the automatic carriage AT moves the tip of the welding torch 4 so that it is aligned with the weld line while spraying flux from the flux spreader 5.

[0029] A groove is provided in the base material 2. A welding voltage Vw is applied between the welding wire 1 and the base material 2, a welding current Iw is passed through, and an arc 3 is generated in a state where the base material is covered with flux.

[0030] Fig. 2 is a timing chart of each signal in the welding device of Fig. 1, illustrating a method for setting welding conditions for submerged arc welding according to an embodiment of the present invention. Fig. 2(A) shows the change over time of the welding start signal St, Fig. 2(B) shows the change over time of the energization determination signal Cd, Fig. 2(C) shows the change over time of the welding voltage setting signal Vr, Fig. 2(D) shows the change over time of the welding current setting signal Ir, Fig. 2(E) shows the change over time of the welding voltage Vw, and Fig. 2(F) shows the change over time of the welding current Iw. The operation of each signal will be explained below with reference to the figures.

[0031] [Test welding operation explanation] The welding operator places the base material 2 and moves the automated carriage AT so that the tip of the welding torch 4 is at the welding start position. The welding operator sets the welding speed by setting the movement speed of the automated carriage AT. The welding operator calculates the time required for welding from the welding length of the base material 2 and the welding speed. The welding operator operates the section elapsed time setting circuit TSR to set the section elapsed time setting signal Tsr, taking into account the time required for welding. In this example, the time required for welding is 3 minutes, and the section elapsed time setting signal Tsr = 1 minute. Therefore, the welding length is divided into sections 1 to 3. The welding operator operates the welding mode selection circuit MS to select the test welding mode. This allows test welding to be performed.

[0032] [Explanation of Section 1] At time t1, when the welding operator turns on the push button of the welding start circuit ST, the welding start signal St changes to a high level, as shown in (A) of the figure. In response to this, the welding power source PS starts, the feeding of welding wire 1 begins, and an arc 3 is generated. As a result, at time t1, the welding voltage Vw reaches an arc voltage value of several tens of volts, as shown in (E) of the figure. As shown in (F) of the figure, the welding current Iw also begins to flow, and the current determination signal Cd changes to a high level, as shown in (B) of the figure. As a result, the section setting signal Sr changes from 0 to 1, entering section 1. Since the section setting signal Sr has counted up, this fact is notified by sound, light, a display, or the like. Because the current determination signal Cd has changed to a high level, the automated carriage AT moves the tip of the welding torch 4 along the weld line, and the flux spreader 5 begins to spread flux. As shown in Figure 1C, when the welding operator adjusts the welding voltage setting signal Vr to Vr1, the welding voltage Vw is controlled to Vr1. As shown in Figure 1D, when the welding operator adjusts the welding current setting signal Ir to Ir1, the welding current Iw becomes Ir1 via the feed speed. The welding voltage Vw and welding current Iw form waveforms that fluctuate up and down in short cycles. The welding condition during the interval is evaluated based on the welding voltage Vw, its fluctuation, the occurrence of a short circuit, the occurrence of an arc interruption, etc., and the welding condition evaluation index signal Wc = Wc1 is calculated. The welding condition evaluation index signal Wc is evaluated lower the greater the fluctuation of the welding voltage Vw. The welding condition evaluation index signal Wc is also evaluated lower when a short circuit occurs, causing the welding voltage Vw to be approximately 0 V. The welding condition evaluation index signal Wc is also evaluated lower when an arc interruption occurs, causing the welding voltage Vw to be approximately 50 V or higher. The signal is a composite value of these.

[0033] [Explanation of Section 2] At time t2, when the elapsed time since time t1 reaches the value of the section elapsed time setting signal Tsr, the section setting signal Sr counts up from 1 to 2, and the system transitions to section 2. At the same time, the welding voltage setting signal Vr=Vr1, welding current setting signal Ir=Ir1, and welding state evaluation index signal Wc=Wc1 at time t2 are combined with the section setting signal Sr=Sr1 and stored as welding condition memory signal Wm=(Sr1, Vr1, Ir1, Wc1). Since the section setting signal Sr has been counted up, this is indicated by sound, light, a display, or the like. At time t21, a short time after time t2, as shown in FIG. 1C, the welding operator, upon receiving this indication, adjusts the value of the welding voltage setting signal Vr to increase it to Vr2, and the welding voltage Vw is controlled to be constant at Vr2. At time t21, as shown in (D) of the same figure, the welding operator adjusts the value of the welding current setting signal Ir to increase it to Ir2, and the value of the welding current Iw becomes Ir2 via the feed speed. The welding voltage Vw and welding current Iw have waveforms that fluctuate up and down in a short cycle. The welding condition during this period is evaluated based on the welding voltage Vw, its fluctuation, the occurrence of short circuits, the occurrence of arc interruption, etc., and the welding condition evaluation index signal Wc = Wc2 is calculated.

[0034] [Explanation of section 3] At time t3, when the elapsed time since time t2 reaches the value of the section elapsed time setting signal Tsr, the section setting signal Sr counts up from 2 to 3, and the system transitions to section 3. At the same time, the welding voltage setting signal Vr=Vr2, welding current setting signal Ir=Ir2, and welding state evaluation index signal Wc=Wc2 at time t3 are combined with the section setting signal Sr=Sr2 and stored as welding condition memory signal Wm=(Sr2, Vr2, Ir2, Wc2). Since the section setting signal Sr has been counted up, this is indicated by sound, light, a display, or the like. At time t31, a short time after time t3, as shown in FIG. 1C, the welding operator, upon receiving this indication, adjusts the value of the welding voltage setting signal Vr to increase it to Vr3, and the welding voltage Vw is controlled to be constant at Vr3. At time t31, as shown in (D) of the same figure, the welding operator adjusts the value of the welding current setting signal Ir to increase it to Ir3, and the value of the welding current Iw becomes Ir3 via the feed speed. The welding voltage Vw and welding current Iw have waveforms that fluctuate up and down in a short cycle. The welding condition during this period is evaluated based on the welding voltage Vw, its fluctuation, the occurrence of short circuits, the occurrence of arc interruption, etc., and the welding condition evaluation index signal Wc = Wc3 is calculated.

[0035] At time t4, the tip of the welding torch 4 reaches the welding end position, and the welder presses the push button on the welding start circuit ST to turn it off. As shown in (A) of the figure, the welding start signal St goes low. In response, the welding power source PS stops outputting power. As shown in (E) of the figure, the welding voltage Vw goes to 0 V, and as shown in (F) of the figure, the welding current Iw goes to 0 A. As a result, as shown in (B) of the figure, the energization determination signal Cd goes low. Because the energization determination signal Cd has gone low, the section setting signal Sr is reset from 3 to 0. At the same time, the welding voltage setting signal Vr = Vr3, the welding current setting signal Ir = Ir3, and the welding condition evaluation index signal Wc = Wc3 at time t4 are combined with the section setting signal Sr = Sr3 and stored as the welding condition memory signal Wm = (Sr3, Vr3, Ir3, Wc3). This completes the test welding.

[0036] [Explanation of actual welding operation] The welding operator operates the welding mode selection circuit MS to select the actual welding mode. The welding operator comprehensively evaluates the welding results, such as the welding state evaluation index signal Wc and the weld bead appearance, for sections 1 to 3 in the test welding and selects the best section. When the welding operator selects a section using the welding condition setting circuit WR, the welding voltage setting signal Vr and welding current setting signal Ir corresponding to that section are set. For example, when section 2 is selected, Vr = Vr2 and Ir = Ir2 are set. The welding operator places the base material 2 for actual welding. Then, when the welding operator turns on the push button of the welding start circuit ST, actual welding begins under the welding conditions of the welding voltage setting signal Vr = Vr2 and welding current setting signal Ir = Ir2.

[0037] The effects of this embodiment are described below. According to this embodiment, a method for setting welding conditions for submerged arc welding, in which welding is performed by applying a welding voltage and welding current while moving the tip position of a welding torch along a weld line, includes a test welding mode and an actual construction welding mode. In the test welding mode, multiple sections are set along the weld line, and welding conditions are adjusted as the tip position of the welding torch moves through each section. When the tip position of the welding torch reaches the end position of each section, the welding conditions at that time are stored for each section and test welding is performed. In the actual construction welding mode, one of the welding conditions stored for each section is selected based on the welding results and actual construction welding is performed. Conventional submerged arc welding requires groove preparation in a thick plate, which requires time-consuming preparation before welding. Furthermore, in submerged arc welding, the arc generating portion is covered by flux, making it impossible to directly observe the welding state. Therefore, it is impossible to determine whether the welding conditions are appropriate without checking the appearance of the bead after welding is completed. As a result, submerged arc welding has a problem in that test welding for setting welding conditions takes time. In this embodiment, multiple sections are provided on a single weld line, the welding conditions are adjusted for each section, and the adjusted welding conditions for each section are stored and used for test welding. After welding is completed, the section with the best welding results is selected, and actual welding is performed using the welding conditions for the selected section. In this way, multiple welding conditions can be tried in one test welding, which makes it possible to set welding conditions efficiently for test welding.

[0038] More preferably, according to this embodiment, the welding conditions include at least the setting conditions of the welding voltage and welding current. The setting conditions of the welding voltage and welding current have a significant effect on the welding result. For this reason, the setting conditions of the welding voltage and welding current are the most important setting conditions of the welding conditions.

[0039] More preferably, according to this embodiment, in the test welding mode, when the tip position of the welding torch reaches the start position of each section, a notification to that effect is given, and while the tip position of the welding torch is moving through each section, the welding operator manually adjusts the welding conditions. Since the start point of each section is notified by sound, light, display, etc., the welding operator can adjust the welding conditions for each section in response to the notification.

[0040] More preferably, according to this embodiment, each section is set based on the elapsed time from the start of welding. The section elapsed time is set, and a section is set by dividing it into sections each time the section elapsed time has elapsed since the start of welding. In this way, there is no need to provide a special sensor or the like for setting the sections, so multiple sections can be set on the weld line inexpensively and easily.

[0041] More preferably, according to this embodiment, when test welding is being performed for each section, an evaluation index for the welding condition is calculated based on at least the welding voltage and stored for each section, and when in actual welding mode, welding conditions are selected based on the evaluation index. During test welding for each section, the welding condition evaluation index is calculated by evaluating fluctuations in the welding voltage, occurrence of short circuits, occurrence of arc interruption, etc. The best section can be selected based on the welding condition evaluation index, which is objective information, making it easy to select the section. [Explanation of symbols]

[0042] 1: Welding wire, 2: Base metal, 3: Arc, 4: Welding torch, 5: Flux spreader, AT: Automatic trolley, CD: Current discrimination circuit, Cd: Current discrimination signal, IR: Welding current setting circuit, Ir: Welding current setting signal, Iw: Welding current, MS: Welding mode selection circuit, Ms: Welding mode signal, PS: Welding power source, SR: Section setting circuit, Sr: Section setting signal, ST: Welding start circuit, St: Welding start signal, TSR: Section elapsed time setting circuit, Tsr: Section elapsed time setting signal, VD: Welding voltage detection circuit, Vd: Welding voltage detection signal, VR: Welding voltage setting circuit, Vr: Welding voltage setting signal, Vw: Welding voltage, Wc: Welding condition evaluation index signal, WF: Welding feeder, WM: Welding condition memory circuit, Wm: Welding condition memory signal, WR: Welding condition setting circuit

Claims

1. A method for setting welding conditions for submerged arc welding in which a welding voltage and a welding current are applied while moving the tip position of a welding torch along a welding line, comprising:

1. A method for setting welding conditions for submerged arc welding, comprising: a test welding mode and a practical welding mode; in the test welding mode, a plurality of sections are set in the weld line; welding conditions are adjusted as the tip position of the welding torch moves through each section; when the tip position of the welding torch reaches an end position of each section, the welding conditions at that time are stored for each section and test welding is performed; and in the practical welding mode, one of the welding conditions stored for each section is selected based on the welding result and practical welding is performed.

2. 2. The method for setting welding conditions for submerged arc welding according to claim 1, wherein the welding conditions include setting conditions for at least the welding voltage and the welding current.

3. 3. The method for setting welding conditions for submerged arc welding according to claim 1, wherein, in the test welding mode, when the tip position of the welding torch reaches a start position of each section, a notification to that effect is given, and when the tip position of the welding torch is moving within each section, a welding operator manually adjusts the welding conditions.

4. 3. The method for setting welding conditions for submerged arc welding according to claim 1, wherein each of the sections is set based on an elapsed time from the start of welding.

5. 3. The method for setting welding conditions for submerged arc welding according to claim 1, wherein an evaluation index for the welding state is calculated based on at least the welding voltage while the test welding is being performed for each section, and the evaluation index is stored for each section, and when the actual welding mode is selected, the welding conditions are selected based on the evaluation index.

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