Pulse arc welding method, welding equipment, and quality control method

Abstract

The present invention provides a pulsed arc welding method and welding apparatus that can sufficiently reduce the generation of spatter. Furthermore, the present invention provides a quality control method that can accurately determine the generation of spatter. [Solution] The pulse arc welding method and welding apparatus of the present invention acquire a current-voltage plot when pulse arc welding is performed, compare the current-voltage plot with a preset appropriate current-voltage plot of welding current and welding voltage to determine the amount of spatter generated, and set the welding conditions for the current or next welding based on the determination result. Furthermore, the pulsed arc welding quality control method of the present invention involves obtaining a current-voltage plot when pulsed arc welding is performed, comparing the current-voltage plot with a preset appropriate current-voltage plot for welding current and welding voltage, determining the amount of spatter generated, and improving the defect rate.

Description

Technical Field

[0001] The present invention relates to a welding method, a welding apparatus, and a quality control method for pulsed arc welding.

Background Art

[0002] In the production of automotive chassis members, pulsed arc welding is frequently used. Further, as a recent trend, in order to improve the electrocoating property and corrosion resistance at the welded portion of the chassis member, an extremely low-Si solid wire is used. The extremely low-Si solid wire has the function of reducing poor electrocoating due to welding slag.

[0003] For example, Patent Document 1 discloses an extremely low silicon welding wire excellent in porosity resistance and electrocoating property, which contains, in terms of mass%, C: 0.001 to 0.30%, Si: 0.001 to 0.1%, Mn: 0.50 to 3.00%, P: 0.030% or less, S: 0.030% or less, and further contains one or more selected from Ni: 0.001 to 0.900%, Cr: 0.001 to 0.100%, Mo: 0.001 to 0.500%, and Cu: 0.50% or less, with the balance being Fe and unavoidable impurities.

[0004] Although the extremely low-Si solid wire has the function of reducing coating defects due to welding slag, on the other hand, a large amount of spatter may occur. When a large amount of spatter adheres to the welded portion and its periphery, the man-hours for removing it increase, which may lead to a decrease in production efficiency.

[0005] As a technique for reducing the generation of such spatter, for example, Patent Document 2 discloses a pulsed arc welding method for welding by pulsed arc welding, which acquires waveform information and the amount of generated spatter when performing pulsed arc welding using a welding wire of a predetermined material, and automatically searches for a pulse waveform in which the amount of spatter is further reduced from these information.

Prior Art Documents

Patent Documents

[0006] [Patent Document 1] Patent No. 6829699 [Patent Document 2] Patent No. 7195993 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] The spatter measurement system described in Patent Document 2 uses a process of observing and measuring the spatter generated from the tip of the welding torch with a camera. However, because arc plasma has an extremely high light intensity, it is extremely difficult to visualize and quantify spatter with low light intensity when the arc plasma is exposed. Therefore, the method in Patent Document 2 cannot accurately measure the amount of spatter, and the accuracy of the correspondence between the amount of spatter and waveform information is low, making it difficult to output appropriate waveform control and thus failing to reduce spatter.

[0008] This invention has been made in view of the above circumstances, and aims to provide a pulse arc welding method and welding apparatus that can sufficiently reduce the generation of spatter. Furthermore, this invention aims to provide a quality control method that can accurately determine the generation of spatter. [Means for solving the problem]

[0009] The present invention includes the following embodiments.

[0010] (Aspect 1) A pulsed arc welding method, A welding process that performs pulsed arc welding, The acquisition process involves obtaining a current-voltage plot of the welding current and welding voltage when the above pulsed arc welding is performed, A determination step is performed to determine the amount of spatter generated by comparing the current-voltage plot obtained in the above acquisition step with the appropriate current-voltage plot for pre-set welding current and welding voltage. A control step that sets the welding conditions for the welding process currently being performed or the next welding process based on the determination result of the above determination step, An arc welding method characterized by including the following:

[0011] (Aspect 2) The arc welding method according to embodiment 1, characterized in that the welding conditions set in the control step are at least one condition selected from the group consisting of welding current, welding voltage, welding speed, wire consumption, pulse frequency, peak time, rise time, fall time, peak current, and base current.

[0012] (Aspect 3) A pulsed arc welding apparatus, The weld area where pulsed arc welding is performed, Includes a control unit for operating the above-mentioned welded part, The above control unit, When the above pulsed arc welding is performed, a current-voltage plot of the welding current and welding voltage is obtained. The amount of spatter generated is determined by comparing the acquired current-voltage plot with the appropriate current-voltage plot for pre-set welding current and welding voltage. An arc welding apparatus characterized by setting welding conditions for the current or next welding operation based on the judgment result.

[0013] (Aspect 4) The arc welding apparatus according to embodiment 3, characterized in that the welding conditions set in the control unit are at least one condition selected from the group consisting of welding current, welding voltage, welding speed, wire consumption, pulse frequency, peak time, rise time, fall time, peak current, and base current.

[0014] (Aspect 5) A quality control method for pulsed arc welding, An acquisition process to obtain a current-voltage plot of the welding current and welding voltage when pulsed arc welding is performed, A determination step of comparing the current-voltage plot obtained in the above acquisition step with a preset appropriate current-voltage plot of welding current and welding voltage to determine the amount of spatter generated, A quality control method, characterized by including this.

[0015] (Aspect 6) The quality control method according to the above aspect 5, further characterized by including a storage step of storing the determination result of the above determination step.

[0016] (Aspect 7) The quality control method according to the above aspect 5 or 6, further characterized by including a display step of displaying the determination result of the above determination step.

Effect of the Invention

[0017] According to the pulse arc welding method and welding apparatus of the present invention, the generation of spatter can be sufficiently reduced. Further, according to the quality control method of pulse arc welding of the present invention, the generation of spatter can be accurately determined.

Brief Description of the Drawings

[0018] [Figure 1] FIG. 1 is a current-voltage plot during welding and a photograph during welding showing the actual spatter generation situation. The photograph during welding is a photograph taken from the side with respect to the welding direction. The same applies to the photographs during welding in FIGS. 2 to 4 below. [Figure 2] FIG. 2 is a photograph in a plan view of the welded bead and its peripheral part after welding in Examples 1 to 4, a photograph during welding showing the actual spatter generation situation, and a diagram showing a current-voltage plot during welding. [Figure 3] FIG. 3 is a photograph in a plan view of the welded bead and its peripheral part after welding in Examples 5 to 8, a photograph during welding showing the actual spatter generation situation, and a diagram showing a current-voltage plot of welding current and welding voltage. [Figure 4]Figure 4 shows a plan view photograph of the weld bead and its surrounding area after welding in Examples 9 to 11, a photograph taken during welding showing the actual spatter generation, and a current-voltage plot of the welding current and welding voltage. [Modes for carrying out the invention]

[0019] To achieve the above objective, the inventors diligently investigated new methods for suppressing spatter generation. As a result, the inventors discovered a unique trend in spatter generation, specifically the unique pulse waveform trends of the welding current and welding voltage, and by feeding back this trend, they found a new welding method and welding apparatus that can sufficiently reduce spatter generation. Furthermore, by utilizing the unique pulse waveform trends of the welding current and welding voltage, the inventors found a new quality control method that can accurately determine the amount of spatter generated.

[0020] The present invention was completed based on the above findings and includes the following embodiments of the pulsed arc welding method, pulsed arc welding apparatus, and pulsed arc welding quality control method.

[0021] First, preferred embodiments of the pulsed arc welding method of the present invention will be described in detail with reference to the drawings. In this specification, pulsed arc welding refers to arc welding performed by periodically increasing and decreasing the current to create a pulsed current waveform.

[0022] <Pulse Arc Welding Method> A pulsed arc welding method according to one embodiment of the present invention includes a welding step of performing pulsed arc welding, an acquisition step of acquiring a current-voltage plot during welding when pulsed arc welding is performed, a determination step of comparing the current-voltage plot acquired in the acquisition step with an appropriate current-voltage plot of a preset welding current and welding voltage to determine the amount of spatter generated, and a control step of setting the welding conditions for the welding step being performed or the next welding step based on the determination result of the determination step.

[0023] In the process of obtaining the above findings, the inventors discovered a correlation between the droplet transfer phenomenon related to spatter generation during welding and the current-voltage plot during welding. Here, Figure 1 shows the current-voltage plot of welding current and welding voltage, and a photograph of the welding process showing the actual spatter generation. The photograph of the welding process was taken from the side with respect to the welding direction.

[0024] In pulsed arc welding, the ideal state in which spatter does not occur is the normal state shown in Figure 1(a). In this normal state shown in Figure 1(a), the droplet transfer phenomenon caused by pulsed arc welding, that is, the phenomenon from droplet formation to droplet growth, droplet constriction, and finally droplet detachment, is repeatedly reproduced. On the other hand, the explosive transfer shown in Figure 1(b) is a transfer mode in which the gas inside the molten droplet expands and ruptures. In this explosive transfer shown in Figure 1(b), the shape of the molten droplet (i.e., arc length) and the corresponding welding voltage change sequentially, so it was found that the plots at the hatched areas are formed in a band shape in the current-voltage plot of the welding current and welding voltage (see the arrow in Figure 1(b)). Furthermore, in the short-circuit transition shown in Figure 1(c), the current-voltage plots of the welding current and welding voltage show an increase in plots below 15V, and it was found that the size of the sputter generated or deposited changes depending on the current range in which these plots are located (0-100A: small current range, 100-200A: small current range, 200-400A: standard current range, 400-700A: large current range). Based on these findings, the inventors discovered that the amount of spatter generated can be determined by comparing the current-voltage plot of the welding current and welding voltage when pulsed arc welding is performed with an appropriate current-voltage plot of the welding current and welding voltage that has been set in advance based on multiple prototypes and actual manufacturing results. Furthermore, the inventors discovered that by setting the welding conditions for the welding process in progress or the next welding process based on this determination result, the welding conditions can be efficiently adjusted to welding conditions that can reduce spatter generation, and as a result, spatter generation in pulsed arc welding can be sufficiently reduced.

[0025] The pulse arc welding method of this embodiment includes the above-described steps. That is, the current-voltage plot of the welding current and welding voltage when pulse arc welding is performed is compared with a preset appropriate current-voltage plot of the welding current and welding voltage to determine the amount of spatter generated. Based on the determination result, the welding conditions for the welding process being performed or the next welding process are set. Therefore, the welding conditions can be efficiently adjusted to welding conditions that can reduce the generation of spatter, and the generation of spatter in pulse arc welding can be sufficiently reduced.

[0026] The following describes in detail each step of the pulse arc welding method according to this embodiment.

[0027] [Welding Process] In this embodiment, the welding process is a process of performing pulsed arc welding using a predetermined welding wire. The pulsed arc welding in this process is not particularly limited, and a general pulsed arc welding method can be employed. For example, the welding process may be performed using a pulsed arc welding apparatus and a welding robot.

[0028] The welding wire used in the welding process is not particularly limited; it can be a general-purpose welding wire or an extremely low-Si welding wire that is prone to spattering.

[0029] (Welding conditions) In the welding process, the welding conditions for pulsed arc welding include the wire consumption W of the welding wire, the pulse frequency f, and the peak time T in the pulse waveform. p , Startup time T up , fall time T down Peak current I p Base current I b These are some examples. The preferred range for these various welding conditions is set for each prerequisite heat input condition, from the viewpoint of ensuring that molten droplets are of an appropriate size and suppressing the generation of irregular beads and spatter.

[0030] [Acquisition process] In this embodiment, the acquisition step is to acquire the welding current and welding voltage when the pulsed arc welding described above is performed. In this step, the means for acquiring the current-voltage plot during welding are not particularly limited, but for example, it may be acquired from data measured by measuring instruments during pulsed arc welding. In addition, welding time, welding wire feeding speed, shielding gas flow rate, etc., may be acquired simultaneously with the welding current and welding voltage.

[0031] [Judgment process] In this embodiment, the determination step is to compare the current-voltage plot obtained in the acquisition step with a preset appropriate current-voltage plot for welding current and welding voltage, and to determine the amount of spatter generated.

[0032] The optimal current-voltage plot for welding current and voltage represents the ideal shape of the current-voltage plot. This plot is set based on welding current and voltage data obtained from multiple prototypes and actual manufacturing results, specifically when spatter generation is absent or at an acceptable level. When setting this optimal current-voltage plot for welding current and voltage, tolerances based on various product quality and production efficiency factors are taken into consideration.

[0033] In the determination process, the means for comparing and determining the two current-voltage plots described above are not particularly limited, but for example, the control unit of the pulse arc welding apparatus may use data stored in memory or the like to compare the two current-voltage plots.

[0034] [Control Process] In this embodiment, the control step is a step of setting the welding conditions for the welding process currently being performed or the next welding process based on the determination result of the determination step described above. In this step, if the determination result of the determination step described above is good, that is, if the determination result is that there is no spatter or the amount is at an acceptable level, the welding conditions may not be changed and the same conditions as those for the welding process currently being performed or the previous welding process may be set. On the other hand, if the determination result of the determination step described above is bad, that is, if the determination result is that there is a lot of spatter, welding conditions that can reduce the amount of spatter are set.

[0035] The welding conditions set in the control process are not particularly limited, but it is preferable that they be at least one condition selected from the group consisting of welding current, welding voltage, welding speed, wire consumption, pulse frequency, peak time, rise time, fall time, peak current, and base current. Since these welding conditions are factors that are thought to be involved in the generation of spatter, it is easy to efficiently and effectively adjust the conditions to reduce the generation of spatter.

[0036] In the control process, the type and content (set values, etc.) of welding conditions to be set can be determined based on data from multiple prototypes or actual manufacturing results. Furthermore, the means for setting the next welding conditions based on the judgment result are not particularly limited, but for example, the control unit of the pulse arc welding apparatus may set the next welding conditions based on the above judgment result.

[0037] Furthermore, the pulse arc welding method of this embodiment may include any steps other than those described above, such as pre-treatment steps and post-treatment steps, which are commonly performed in pulse arc welding.

[0038] As described above, the pulse arc welding method of this embodiment is a welding method that can sufficiently reduce the generation of spatter. This is true not only when using general-purpose welding wire, but also when using extremely low Si welding wire, which is prone to spatter generation.

[0039] The pulse arc welding method of this embodiment can be carried out using the pulse arc welding apparatus of the embodiment described later.

[0040] Next, a pulse arc welding apparatus, which is another embodiment of the present invention, will be described.

[0041] <Pulse Arc Welding Equipment> A pulse arc welding apparatus according to one embodiment of the present invention is a welding apparatus that includes a welding unit for performing pulse arc welding and a control unit for operating the welding unit. Furthermore, the control unit in this embodiment acquires a current-voltage plot of the welding current and welding voltage when pulse arc welding is performed, compares the acquired current-voltage plot with a preset appropriate current-voltage plot of welding current and welding voltage to determine the amount of spatter generated, and sets the welding conditions for the current or next welding based on the determination result.

[0042] In this embodiment of the pulse arc welding apparatus, since it also includes the control unit described above, the current-voltage plot when pulse arc welding is performed is compared with a preset appropriate current-voltage plot of welding current and welding voltage, the amount of spatter generated is determined, and the welding conditions for the current or next welding process are set based on the determination result. As a result, the welding conditions can be efficiently adjusted to welding conditions that can reduce the generation of spatter, and the generation of spatter in pulse arc welding can be sufficiently reduced.

[0043] The following describes in detail each component of the pulse arc welding apparatus of this embodiment.

[0044] [Welded joint] In this embodiment, the welding unit is the part of the welding apparatus that performs pulsed arc welding. The welding unit is not particularly limited as long as it is configured to perform pulsed arc welding, and a welding unit of a general pulsed arc welding apparatus can be used. Examples of such a welding unit include a welding robot equipped with a welding torch. Such a welding robot operates based on commands output from a control unit and can perform the pulsed arc welding described above. Alternatively, the welding unit may be a welding torch fixed to the welding apparatus. In this case, the welding apparatus itself may be configured to be movable.

[0045] [Control Unit] In this embodiment, the control unit operates the welding section of the welding apparatus and acquires a current-voltage plot when pulse arc welding is performed. It compares the acquired current-voltage plot with a preset optimal current-voltage plot for welding current and welding voltage (i.e., the ideal shape of the current-voltage plot) to determine the amount of spatter generated, and based on the determination result, sets the welding conditions for the current or next welding operation.

[0046] In the control unit, if the determination result for the amount of spatter generated is good, that is, if the determination result is that there is no spatter or the amount is at an acceptable level, the welding conditions may be left unchanged and the same conditions may be set. On the other hand, if the determination result is bad, that is, if the determination result is that there is a lot of spatter generated, welding conditions that can further reduce the amount of spatter generated are set.

[0047] The control unit is not particularly limited as long as it is configured to function as described above, but examples include a control circuit comprising a memory (storage unit) such as a hard disk or semiconductor non-volatile memory in a computer located inside or outside the pulse arc welding apparatus, a central processing unit (CPU), and peripheral circuits. Furthermore, the memory may store various data and programs, such as an operation program for the welding unit, a data acquisition processing program for acquiring the current-voltage plot data during welding as described above, data for the appropriate current-voltage plot of the welding current and welding voltage set in advance, a determination processing program for determining the amount of spatter generated by comparing the acquired current-voltage plot with the appropriate current-voltage plot, and a welding condition setting processing program for setting the welding conditions for the current or next welding based on the determination result of the amount of spatter generated.

[0048] The welding conditions set in the control unit are not particularly limited, but it is preferable that they be at least one condition selected from the group consisting of welding current, welding voltage, welding speed, wire consumption, pulse frequency, peak time, rise time, fall time, peak current, and base current. Since these welding conditions are factors that are thought to be involved in the generation of spatter, it is easy to efficiently and effectively adjust the conditions to reduce the generation of spatter.

[0049] In addition to the welding unit and control unit described above, the pulse arc welding apparatus of this embodiment may also have components and devices that are typically found in pulse arc welding apparatuses. Examples of such components and devices include a display unit such as a display, and an input unit such as a touch panel or keyboard.

[0050] Next, a further embodiment of the present invention, a method for quality control of pulsed arc welding, will be described in detail.

[0051] <Quality control method> A pulsed arc welding quality control method according to one embodiment of the present invention includes an acquisition step of acquiring a current-voltage plot when pulsed arc welding is performed, and a determination step of comparing the current-voltage plot acquired in the acquisition step with an appropriate current-voltage plot of a preset welding current and welding voltage to determine the amount of spatter generated.

[0052] The pulse arc welding quality control method of this embodiment includes the acquisition and determination steps described above. Specifically, the current-voltage plot obtained when pulse arc welding is performed is compared with a preset appropriate current-voltage plot for welding current and welding voltage to determine the amount of spatter generated. As a result, the generation of spatter can be determined with high accuracy. Consequently, the defect rate can be improved.

[0053] The following describes in detail each step of the quality control method of this embodiment.

[0054] [Acquisition process] In this embodiment, the acquisition step is to acquire a current-voltage plot when pulsed arc welding is performed. In this embodiment as well, the means for acquiring the current-voltage plot during welding are not particularly limited, but for example, it may be acquired from data measured by measuring instruments during pulsed arc welding.

[0055] [Judgment process] In this embodiment, the determination step is to compare the current-voltage plot obtained in the acquisition step described above with an appropriate current-voltage plot of a preset welding current and welding voltage, and to determine the amount of spatter generated.

[0056] In this embodiment as well, the appropriate current-voltage plot for welding current and welding voltage is the ideal shape of the current-voltage plot. This plot is set based on welding current and welding voltage data obtained from data such as multiple prototypes and actual manufacturing results, where spatter generation is absent or at an acceptable level. When setting this appropriate current-voltage plot for welding current and welding voltage, tolerance ranges based on various product quality and production efficiency are taken into consideration.

[0057] In this embodiment as well, the means for comparing the two current-voltage plots described above are not particularly limited, but for example, the control unit of the pulse arc welding apparatus may use data stored in memory or the like to compare the two current-voltage plots.

[0058] In the judgment process, a result indicating no spatter or an acceptable level of spatter is judged as "good." On the other hand, a result indicating a large amount of spatter is judged as "bad." Alternatively, the amount of spatter, such as "no spatter," "little spatter," or "a lot of spatter," can be used directly as the judgment result. The judgment result is used for quality control of pulsed arc welding.

[0059] In the determination step, the means for comparing and determining the two current-voltage plots described above are not particularly limited, but for example, the control unit of the pulse arc welding apparatus may compare the two current-voltage plots using data stored in memory or the like. In this case, the control unit is not particularly limited as long as it is configured to perform at least the determination step of this embodiment, but examples include a control circuit equipped with a memory (storage unit) such as a hard disk or semiconductor non-volatile memory in a computer located inside or outside the pulse arc welding apparatus, a central processing unit (CPU), and peripheral circuits. Furthermore, the memory may store various data and programs such as a data acquisition processing program for acquiring the current-voltage plot data of the welding current and welding voltage described above, data for the appropriate current-voltage plot of the welding current and welding voltage set in advance, and a determination processing program for determining the amount of spatter generated by comparing the acquired current-voltage plot with the appropriate current-voltage plot.

[0060] Furthermore, the quality control method of this embodiment may further include any additional steps related to quality control. Examples of such steps include a storage step and a display step. That is, the quality control method of this embodiment may further include a storage step for storing the judgment result of the judgment step described above, or it may further include a display step for displaying the judgment result of the judgment step described above. These steps will be described below.

[0061] [Preservation process] The storage step is the step of saving the determination result from the determination step described above. The means for saving the determination result are not particularly limited, but for example, the determination result may be saved in the memory of the control unit of the pulse arc welding apparatus.

[0062] The judgment results saved in the storage process may be used as record data for quality control, as auxiliary data (feedback data) when setting welding conditions, or as data for setting appropriate current-voltage plots for welding current and welding voltage.

[0063] [Display process] The display step is a step of displaying the judgment result of the judgment step described above. The means for displaying the judgment result are not particularly limited, but for example, the judgment result may be displayed on a display unit such as a display provided in the pulse arc welding apparatus.

[0064] The judgment results displayed in the display process may be displayed as quality control record data, as a warning display during manufacturing, as auxiliary data (feedback data) when setting welding conditions, or as setting data for the appropriate current-voltage plot of welding current and welding voltage.

[0065] (Examples of application) As described above, the pulse arc welding method and welding apparatus of the present invention can sufficiently reduce the generation of spatter. Furthermore, the quality control method for pulse arc welding of the present invention can accurately determine the generation of spatter. For this reason, the pulse arc welding method, welding apparatus, and quality control method of the present invention can be applied not only to the chassis members of automobiles mentioned above, but also to the manufacturing sites of various parts in various fields, such as various structural elements of buildings; various structural components of transportation machinery such as automobiles, aircraft, and ships (e.g., tanks); and various structural components of industrial machinery.

[0066] The pulse arc welding method, welding apparatus, and quality control method of the present invention are not limited to the embodiments described above or the examples described later, and can be appropriately combined, substituted, or modified without departing from the purpose and spirit of the present invention. [Examples]

[0067] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to such examples.

[0068] In performing pulsed arc welding according to an embodiment of the present invention, first, various devices were prepared as means for acquiring current-voltage plots of the welding current and welding voltage during pulsed arc welding.

[0069] (Means for acquiring current-voltage plots of welding current and welding voltage) An AC / DC current probe (HIOKI CT6845A) of a current sensor clamped to the ground wire, a sensor unit (HIOKI CT9555), and a data logger (KEYENCE NR-500) equipped with a measurement unit that converts potential difference into current for input were connected in this order. Wiring was installed to the ground and the welding torch to acquire the potential difference between them, and this potential difference was converted into current by the data logger. Furthermore, a personal computer was connected to the data logger.

[0070] (Pulse arc welding) Pulse arc welding was performed under the welding conditions described below, and the current-voltage plots of the welding current and welding voltage were obtained using the acquisition method described above.

[0071] (Welding conditions) Average welding current: 200A Average welding voltage: 22.5V Welding speed: 1 m / min Wire feeding speed: 7.0 m / min Wire protrusion length: 15mm Torch tilt angle: 60° Gas type: Ar + 20% CO2 Gas flow rate: 20 L / min Welding mode: Pulse welding

[0072] Similarly, pulse arc welding was performed a total of 11 times (including the first time) with varying welding conditions, and current-voltage plots of the welding current and welding voltage for each were obtained. These 11 pulse arc welding sessions are designated as Examples 1 to 11, and the current-voltage plots of the welding current and welding voltage for Examples 1 to 11 are shown in Figures 2 to 4. Note that (1) to (4) in Figure 2 correspond to Examples 1 to 4, (5) to (8) in Figure 3 correspond to Examples 5 to 8, and (9) to (11) in Figure 4 correspond to Examples 9 to 11. Furthermore, in the current-voltage plots on the right side of Figures 2 to 4 (1) to (11), the vertical axis is voltage (V) and the horizontal axis is current (A).

[0073] Furthermore, during pulsed arc welding in Examples 1 to 11, the welded area was photographed with a camera from the side relative to the welding direction to obtain photographs showing the spatter generation during pulsed arc welding. To facilitate the visualization of spatter generation, a light-shielding plate that blocks the arc plasma was placed in front of the welded area during photography. Furthermore, photographs of the weld bead and its surrounding area after pulse arc welding in Examples 1 to 11 were taken with a camera in a plan view.

[0074] Furthermore, the spatter generation during pulse arc welding was confirmed from photographs taken during pulse arc welding in Examples 1 to 11, and the spatter adhesion after pulse arc welding was confirmed from plan view photographs of the weld bead and its surrounding area after welding. These photographs are shown in Figures 2 to 4 (1) to (11), respectively. In each of Figures 2 to 4 (1) to (11), the center photograph is a photograph taken during welding, and the photograph on the left is a plan view photograph of the weld bead and its surrounding area.

[0075] The changes in welding conditions and the occurrence of spatter in Examples 1 to 11 are as follows:

[0076] Example 1 is a welding test performed under the standard welding conditions described above. In Example 1, as shown in Figure 2(1), a large amount of spatter is generated during welding.

[0077] Example 2 is an example in which the average welding voltage was increased. In Example 2, the arc length increased and spatter due to short circuits decreased, resulting in a current-voltage plot distribution that was close to the ideal shape (optimal current-voltage plot), as shown in Figure 2(2).

[0078] Example 3 is an example in which the proportion of oxidizing gas (CO2 or O2) contained in the shielding gas was reduced. In Example 3, the arc length was extended due to the decrease in the proportion of oxidizing gas. As a result, in Example 3, sputtering due to short circuits was reduced, and as shown in Figure 2 (3), the distribution of the current-voltage plot became closer to the ideal shape, and explosive transfer was also reduced.

[0079] Example 4 is an example in which the pulse frequency is increased while keeping the wire consumption the same as in Example 1. In Example 4, the size of the molten droplets formed per pulse became smaller, and sputtering due to short circuits was reduced, resulting in a current-voltage plot distribution that was close to the ideal shape, as shown in (4) of Figure 2.

[0080] Example 5 is an example in which the peak time of the pulse waveform was shortened. In Example 5, the shorter peak time of the pulse waveform, which affects droplet generation and growth, resulted in a smaller droplet size, and as shown in Figure 3 (5), sputtering due to short circuits was reduced, and explosive migration was also reduced.

[0081] Example 6 is an example in which the peak current of the pulse waveform was increased. In Example 6, the peak current of the pulse waveform, which affects droplet generation and growth, was increased, and it is thought that droplet detachment was promoted. As a result, in Example 6, short-circuit migration and explosive migration were reduced, as shown in Figure 3(6).

[0082] Example 7 is an example in which the fall time of the pulse waveform is shortened. In Example 7, shortening the fall time speeds up the extinction of the arc plasma and prevents excessive current from flowing when the droplets detach. As a result, in Example 7, as shown in Figure 3 (7), sputtering due to short circuits is reduced, the distribution of the current-voltage plot approaches the ideal shape, and explosive transfer is also reduced.

[0083] Example 8 is an example in which the surface tension of the molten droplet was increased. In Example 8, the molten droplet formed at the tip of the welding wire became spherical, and the distance from the lower end of the droplet to the molten pool was extended. As a result, as shown in Figure 3 (8), spatter due to short circuits was reduced, and explosive transfer was also reduced.

[0084] Example 9 is an example in which the viscosity of the molten droplet was increased. In Example 9, the increased viscosity extended the distance from the bottom of the molten droplet to the molten pool when the droplet detached, resulting in a reduction in spatter due to short circuits, as shown in Figure 4 (9), and also a reduction in explosive transfer.

[0085] In Example 10, the shorter peak time of the pulse waveform, which affects droplet generation and growth, resulted in a smaller droplet size and a reduction in short circuits, as shown in Figure 4 (10).

[0086] Example 11 is an example of optimizing the wire's target position. By moving the wire's target position further away from the steel plate (molten pool), the arc length was increased, resulting in a reduction in spatter due to short circuits, as shown in Figure 4 (11).

[0087] As described above, the results from Examples 1 to 11 confirmed that there is a correlation between the droplet transfer phenomenon related to spatter generation during welding and the current-voltage plot during welding, and that the amount of spatter generated can be accurately determined by comparing the current-voltage plot during welding with the ideal shape (appropriate current-voltage plot). Furthermore, it was suggested that by setting the welding conditions for the welding process in progress or the next welding process based on this determination result, it may be possible to significantly reduce the generation of spatter in pulsed arc welding.

Claims

1. A pulsed arc welding method, A welding process that performs pulsed arc welding, An acquisition step to acquire the distribution of the current-voltage plot of the welding current and welding voltage when the pulse arc welding is performed, A determination step involves comparing the shape of the current-voltage plot distribution obtained in the acquisition step with the ideal shape of the appropriate current-voltage plot distribution for welding current and welding voltage, which is set in advance considering the tolerance range based on product quality or production efficiency, and determining the amount of spatter generated. A control step that sets the welding conditions for the welding process currently being performed or the next welding process based on the determination result of the determination step, An arc welding method characterized by including the following:

2. The arc welding method according to claim 1, characterized in that the welding conditions set in the control step are at least one condition selected from the group consisting of welding current, welding voltage, welding speed, wire consumption, pulse frequency, peak time, rise time, fall time, peak current, and base current.

3. A pulsed arc welding apparatus, The weld area where pulsed arc welding is performed, Includes a control unit for operating the welded portion, The control unit, When the pulsed arc welding described above is performed, the current-voltage plot distribution of the welding current and welding voltage is obtained. The amount of spatter generated is determined by comparing the shape of the distribution of the acquired current-voltage plot with the ideal shape of the distribution of the appropriate current-voltage plot for welding current and welding voltage, which is set in advance considering the tolerance range based on product quality or production efficiency. An arc welding apparatus characterized by setting welding conditions for the current or next welding operation based on the judgment result.

4. The arc welding apparatus according to claim 3, characterized in that the welding conditions set by the control unit are at least one condition selected from the group consisting of welding current, welding voltage, welding speed, wire consumption, pulse frequency, peak time, rise time, fall time, peak current, and base current.

5. A quality control method for pulsed arc welding, An acquisition process to obtain the distribution of the current-voltage plot of the welding current and welding voltage when pulsed arc welding is performed, A determination step involves comparing the shape of the current-voltage plot distribution obtained in the acquisition step with the ideal shape of the appropriate current-voltage plot distribution for welding current and welding voltage, which is set in advance considering the tolerance range based on product quality or production efficiency, and determining the amount of spatter generated. A quality control method characterized by including the following.

6. The quality control method according to claim 5, further comprising a storage step for storing the determination result of the determination step.

7. The quality control method according to claim 5 or 6, further comprising a display step for displaying the determination result of the determination step.

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