JP2009028775A - Pulse arc welding method and pulse arc welding apparatus - Google Patents

Abstract

The present invention provides a pulse arc welding method and a pulse arc welding apparatus capable of performing accurate and quantitative evaluation of an arc in a short time and performing high-quality and stable pulse arc welding.
A welding power source 3 capable of applying a voltage for generating an arc between a wire 1 and a base material 2 and an imaging capability of 2000 frames / second or more, imaging the arc and image data. A high-speed video camera 12 for capturing a droplet, a droplet size / spatter amount analysis program 23 for processing the image data to analyze the droplet size and spatter generation amount, and an optimum pulse time From the quality determination program 24, the welding power source control program 21 for controlling the pulse waveform to the optimum pulse time, and the high-speed video camera control program 25 for controlling the high-speed video camera 12, pulse arc welding is performed. Apparatus 100 was configured.
[Selection] Figure 1

Description

  The present invention relates to a pulse arc welding method and a pulse arc welding apparatus such as MAG pulse welding and MIG pulse welding.

  Conventionally, in pulsed arc welding, the spatter that is scattered is visually observed, the spatter is collected in a box, measured and quantified, and waveforms such as welding current and arc voltage are sampled at high speed, and their values fluctuate. By checking this, welding workability was evaluated. In addition, using a high-speed video camera, the welding arc phenomenon has been evaluated by photographing the behavior from droplet growth to detachment, the undulation of the molten pool, and the like.

  Evaluation of these observation results was performed by human senses, or qualitatively evaluated the short-time behavior of the arc phenomenon. And based on such evaluation, manually map the relationship between the welding conditions such as pulse current (pulse voltage) and pulse width and the evaluation result of the welding arc phenomenon, create a map of the appropriate pulse area, The welding conditions have been optimized.

  Further, it is known that image processing is performed on an image captured using a welding condition monitoring device, the quality of the welding state is determined from information obtained from the processing result, and the welding conditions are controlled by a method such as feedback control ( For example, see Patent Document 1). The specific method described in Patent Document 1 is to take a picture of the welding situation in synchronization with the base current time when the current value of pulse welding falls to the base current, and to take the photographed image into an image processing device and binarize it. If there is a difference between the reference data and the information obtained from the processing results, the welding current is changed to correct the difference. The automatic welding is performed by performing feedback control so that the welding state is constant.

JP-A-7-185810

  However, the evaluation of the welding arc phenomenon by human sense has individual differences, the evaluation standard varies depending on the person, there is a limit to the ability of human identification, and there is a problem that the amount of information obtained is small. In addition, short-term qualitative evaluation has a problem of lack of reliability. In addition, there is a problem that it takes a lot of time to create a map of an appropriate pulse region as described above.

  Further, as described in Patent Document 1, when determining whether the welding state is good or bad by the image processing apparatus, only a part of the arc phenomenon is photographed as when the photographing of the welding state is the base current time. Therefore, the complicated arc phenomenon cannot be accurately grasped. In the conventional image processing apparatus, since it takes a lot of time to process one screen, there is a problem in that it is difficult to continuously capture and accurately analyze the arc phenomenon.

  The problem to be solved by the present invention is to provide a pulse arc welding method and a pulse arc welding apparatus capable of accurately performing an arc evaluation in a short time and capable of performing high quality and stable pulse arc welding. And

  The pulse arc welding method according to the present invention is a pulse arc welding method in which a voltage is applied to a wire and a base metal from a welding power source to perform arc welding. Image data is obtained by imaging an arc at an imaging speed of several seconds per second, image processing is performed on the image data of the arc, and at least one of the transition state of the droplet or the occurrence state of spatter is analyzed, and the analysis result The gist is to determine whether the welding state is good or not using feedback control, set an optimum pulse time for obtaining an optimum welding state, and perform welding using the optimum pulse time.

  In the pulse arc welding method, the analysis of the state of transition of the droplet or the occurrence of spatter is to determine the relationship between the droplet size and the pulse time or the relationship between the amount of sputtering and the pulse time. It is preferable.

  The pulse arc welding apparatus according to the present invention has a welding power source capable of applying a voltage for generating an arc between a wire and a base material, and an imaging capability of at least the number of frames / second faster than the frequency of the pulse current. A high-speed video camera for capturing the image data by capturing the arc, and processing the image data captured by the high-speed video camera, at least one of the transition state of the droplets or the occurrence of spatter Image analysis means for analyzing the quality, and quality determination means for determining the quality of the welding situation using the analysis result of the image analysis means and setting the optimum pulse time for performing the feedback control and obtaining the optimum welding situation And a welding power source control means for controlling the voltage applied by the welding power source to the optimum pulse time.

  The pulse arc welding apparatus preferably includes an arc voltage setting means for sampling the arc voltage and feeding back the sampled arc voltage to automatically set the spraying arc voltage.

  The pulse arc welding method according to the present invention uses a high-speed video camera to image an arc at an imaging speed of at least the number of frames / second faster than the frequency of the pulse current to obtain image data. Optimal pulse that performs image processing, analyzes at least one of the droplet transfer status or spatter generation status, determines the quality of the welding status using the analysis result, and performs feedback control to obtain the optimal welding status By adopting the method of setting the time, it is possible to accurately evaluate the arc phenomenon in a short time and to perform high-quality and stable arc welding.

  That is, according to the method of the present invention, by adopting a method of imaging an arc at an imaging speed of a number of frames / second faster than the frequency of the pulse current and imaging the arc phenomenon with a high-speed video camera, Compared to the case where conventional arc imaging is performed with a video camera with an imaging speed of about 30 frames / second, it is possible to accurately detect the droplets generated during arc welding and perform quantitative analysis. .

  That is, in the pulse arc welding, it is ideal that one droplet is generated in one cycle including the peak time of the pulse and the base time. Assuming that 200 droplets are generated per second when the period of the pulse current is 200 Hz, it is necessary to capture an image of 200 frames / second or more in order to reliably capture all the droplets as an image. is there. On the other hand, when the imaging capability of the video camera is 30 frames / second, it is impossible to reliably capture 200 droplets / second as an image. However, in the method of the present invention, since the arc is imaged at an imaging speed faster than the frequency of the pulse current, the droplet generated at 200 / sec can be reliably captured and image processing can be performed. .

  In the pulse arc welding method of the present invention, since the above-mentioned optimum pulse time can be set in a short time, even if various welding conditions change, the optimum pulse time is set immediately and a high-quality and stable pulse Arc welding can be performed.

  A pulse arc welding apparatus according to the present invention includes a high-speed video camera having an imaging capability of at least the number of frames / second faster than the frequency of the pulse current and capturing the image data by imaging the arc, and at least a droplet Image analysis means for analyzing any one of the transition state or spatter occurrence state, pass / fail judgment means for setting the optimum pulse time for obtaining the optimum welding situation, and the voltage applied by the welding power source Since the welding power source control means for controlling to the optimum pulse time is provided, the optimum pulse time can be reliably obtained in a short time, and stable high-quality pulse arc welding can be reliably performed. it can.

  Hereinafter, a pulse arc welding apparatus according to an embodiment of the present invention will be described in detail. FIG. 1 is a block diagram showing an outline of an embodiment of a pulse arc welding apparatus. As shown in FIG. 1, the pulse arc welding apparatus 100 applies a voltage from a welding power source 3 to a wire 1 and a base material 2 to generate an arc between the wire 1 and the base material 2.

  In the welding apparatus 100 shown in FIG. 1, the welding wire 1 is fixed to the welding torch 4 and from the wire storage container 6 filled with the wire roll 5 via the conduit cable 7, the wire feeding device 8 and the conduit cable 9. Connected to be supplied.

  A wire from a welding power source 3 for applying a DC voltage is connected to the wire 1 and the base material 2. A voltmeter 10 is provided between the wire 1 and the base material 2, and an ammeter 11 is provided between the welding power source 3 and the welding torch 4.

  Although not particularly illustrated, a gas ejection hole for ejecting a shield gas is provided at the tip of the welding torch 4 so that the outer periphery of the wire 1 and the arc A is covered with the shield gas, and the wire 1 and the arc A are exposed from the atmosphere. It is configured to shield. As a basic configuration of such a pulse arc welding apparatus, any apparatus capable of performing pulse arc welding such as MAG welding such as carbon dioxide gas welding, mixed gas welding, and MIG welding may be used. it can.

  The welding apparatus 100 is provided with a high-speed video camera 12 for photographing an arc generated between the wire 1 and the base material 2, and the high-speed video camera 12 inputs the photographed image and performs image processing. Is connected to a personal computer 20 (hereinafter also referred to as a PC). In addition to the high-speed video camera 12, the PC 20 is connected to a welding power source 3, a voltmeter 10, etc., and a welding power source control program 21, a high-speed video camera control program 25, an arc voltage calculation processing program 22, Various programs such as a droplet size / spatter amount analysis program 23 and a pass / fail judgment program 24 for judging the quality of an arc are stored.

  By executing the control program 21 for the welding power source, it functions as a welding power source control means for controlling the optimum pulse time in the pulse waveform of the welding current. Also, by executing the control program 25 of the high-speed video camera, it is possible to control on / off of the imaging of the arc droplet transfer image of the high-speed video camera and to control the image capture by transmitting the image data to the PC 20. It functions as a control means for a high-speed video camera.

  Further, by executing the arc voltage calculation processing program 22, it functions as an arc voltage setting means capable of automatically setting the spraying arc voltage by feeding back the voltage sampled by the voltmeter 10. In addition, by executing the droplet size / sputter amount analysis program 23, the image data captured by the high-speed video camera 12 is processed to function as an image analysis means for analyzing the droplet size and the amount of spatter. To do. Also, by executing the quality judgment program 24 for judging the quality of the arc, the quality of the welding situation is judged using the analysis result of the image analysis means, and the optimum pulse time for obtaining the optimum welding situation by performing the feedback processing is determined. It functions as a pass / fail judgment means for setting.

  Although not shown, the PC 20 includes a storage device for storing the above-described various programs and recording imaging data of an arc phenomenon captured by the high-speed video camera 12.

  As the PC 20, for example, a commercially available PC (personal computer) having an operating frequency of about 2 GHz equipped with a Pentium 4R (registered trademark of Intel Corporation) as a CPU can be used.

  As the high-speed video camera 12, a camera having an imaging speed of 2000 frames / second or more is used in order to be able to photograph an arc phenomenon of pulse welding in which droplet transfer is repeated at several hundred Hz. For example, since pulse arc welding usually has a pulse current cycle of several hundred Hz, a phenomenon occurs in which several hundred droplets per second are transferred from a wire to a base material in an arc. On the other hand, if there is an imaging capability of 2000 frames / second or more, the occurrence state of several hundred droplets / second can be reliably recorded as an image.

  As such a high-speed video camera, for example, model MARECAM fx-6000 which is a high-speed digital video camera manufactured by NAC Imaging Technology Co., Ltd. can be mentioned. This high-speed video camera has a color CMOS sensor of 3/4 inch and 260,000 pixels, has an imaging speed of 6000 frames per second, and can capture effective pixels at horizontal 512 pixels × vertical 386 pixels.

  The arc imaging using the high-speed video camera 12 is performed as follows. When the welding power source control program 21 and the high-speed video camera control program 25 are executed and the PC 20 receives a welding start trigger signal from the welding power source 3, the arc droplets from the high-speed video camera 12 are delayed after a certain time delay. Start capturing the moving image. Image data captured by the high-speed video camera 12 is recorded in a flash memory in the high-speed video camera 12 at 10 bits / pixel. In this case, it is possible to capture a maximum of 2.5 seconds with one imaging. The recorded image data is transferred to the PC 20 for each welding and stored in a dedicated file format in a storage device or the like in the PC 20.

  The droplet transfer phenomenon is analyzed by executing the droplet size / spatter amount analysis program 23 and performing image processing on the image data stored in the dedicated file format. This image processing can be performed by converting a data file in a dedicated file format into a file format such as AVI format. The high-speed video camera that captures the image data, welding power source control, image processing (analysis of droplet size and spatter amount), and pass / fail judgment processing are performed on one PC. Processing may be performed by a separate PC.

  As the droplet size / spatter amount analysis program 23 for analyzing the droplet transfer phenomenon, image processing software for image processing of the droplet transfer moving image captured by the high-speed video camera 12 was made by himself. This software was created using LabView (Ver 7.1), which is a program development environment commercially available from National Instruments.

FIG. 2 is a flowchart showing the procedure of the pulse arc welding evaluation method. An embodiment of the pulse arc welding method will be described with reference to the flowchart shown in FIG. In the pulse arc welding of the present invention, prior to the main welding, preliminary welding for setting a pulse time is first performed, and an optimum pulse time that is an optimum welding condition is set. Table 1 summarizes the welding conditions and welding equipment used in the examples.

  As shown in FIG. 2, first, basic welding conditions are set (S100). Welding conditions include fixed conditions and variable conditions. The fixed conditions are wire feed speed (welding current), peak current Ip, and base current Ib. Further, the fluctuation conditions are an arc voltage and a pulse time Tp. The arc voltage is set to an initial value of 16V, and is increased by 0.5V step in an arc voltage automatic setting step (S400) described later. The pulse time Tp is set to an initial value of 0.6 ms and is increased in 0.1 ms steps in a pulse time resetting step (S750) described later. Hereinafter, the pulse time will be described.

  FIG. 3 is an explanatory diagram showing a pulse waveform of the welding current. As shown in FIG. 3, when a voltage is applied between the wire 1 and the base material 2, the welding apparatus 100 flows a welding current having a pulse waveform that repeats the base current value Ib and the peak current value Ip at regular time intervals. As a result, an arc phenomenon occurs. The time of the peak current value Ip shown in FIG. 3 is the pulse time Tp. The time indicated by Tc in the figure is the time of one cycle of the pulse.

  4 (a), 4 (b), and 4 (c) are explanatory views showing the form of droplets at points a, b, and c in the pulse waveform of the welding current in FIG. As shown in FIG. 4A, an arc A is generated between the wire 1 and the base material 2 at the start point of the peak current value Ip (point a in FIG. 3), and the tip of the wire 1 is generated by the arc A. 1a melts. Further, as shown in FIG. 4 (b), the wire tip 1 is melted until the welding current becomes the peak current value Ip and the peak time Tp ends (point b in FIG. 3). Grows to a size of 13. When the peak current value Ip is changed to the base current value Ib (point c in FIG. 3), as shown in FIG. 4C, the droplet 13 formed by melting the wire tip 1a becomes a part of the base material 2 immediately below the arc. It is dripped at the molten pool 14 formed by melting the welded portion. Then, after the welding torch 4 moves and the arc passes through the welded portion, the molten pool 14 is cooled and becomes a bead, and the base material 2 is welded.

  At this time, as shown in FIGS. 4A to 4C, it is ideal that one droplet sprays from the wire 1 to the base material 2 per one peak current value Ip. It is. Moreover, the frequency of occurrence of spatter is high when a short circuit is opened, when an instantaneous short circuit occurs, or when the droplets are inappropriately detached. In order to ensure good arc stability and good welding, it is important to find and set an appropriate pulse time so that the amount of spatter generated is reduced and ideal spray transfer is performed.

  As shown in FIG. 2, when the welding condition (initial value) in S100 is set, arc activation is performed under the condition to start welding (S200). Next, the arc voltage is measured by the voltmeter 10, the measurement data is transmitted to the PC 20, and the arc voltage is sampled (S300). In the spray arc voltage automatic setting process (S400), the arc voltage sampled in S300 is fed back to adjust the arc voltage to a predetermined voltage (spray arc voltage).

  FIG. 5 is a graph showing the relationship between the arc voltage and the number of short circuits. As shown in FIG. 5, in the arc arc welding, when the arc voltage is increased, the short circuit is reduced. Then, spraying occurs when the short circuit disappears. The spraying arc voltage is the arc voltage at which this spraying occurs. The spray arc voltage automatic setting process (S400) is specifically performed as follows. FIG. 12 is a graph showing the relationship between arc voltage and time. As shown in FIG. 12, when the voltage value of the arc voltage with respect to time is sampled and monitored, there is a point that, when sputtering occurs, a short circuit occurs and an instantaneous voltage drop occurs. This is the place where spatter occurs. In the first half of FIG. 12, spatter is often generated. However, when the voltage is increased while monitoring the arc voltage, short-circuiting hardly occurs as in the latter half of FIG. 12, and spatter is reduced. . And the voltage when the frequency | count of a short circuit becomes zero within predetermined time (0.25 s) is set as a spraying arc voltage.

  The set value of the spraying arc voltage in S400 is set to an arc voltage at which there is no short circuit and completely sprayed in order to optimize the welding conditions. It is preferable that the arc voltage is set to the following value. If the arc voltage is set a little lower, it is less susceptible to various changes and fluctuations due to disturbances and internal disturbances, and more stable welding can be performed. The reason for this will be described below.

  In general, the arc length increases as the arc voltage increases, and the arc length decreases as the arc voltage decreases. The welding bead shape becomes a narrow bead shape when the arc length is short, and becomes a wide bead shape when the arc length is long. If the bead shape becomes excessively wide, humping tends to occur, and the weld metal may solidify without being properly filled. If the arc voltage is low and the arc length is short, there is no such concern. For this reason, it is preferable that the arc voltage is set slightly lower than the voltage at which spraying occurs completely, so that a short circuit occurs. This specific preferred voltage range is in the range of minus 0.5V to 1.5V with respect to the voltage at which spraying occurs completely. In this way, welding can be performed in a state where the spraying arc voltage is set to spray transfer without short-circuiting by the process of sampling and feedback controlling the spraying arc voltage and adjusting the voltage.

  As shown in FIG. 2, after the automatic setting of the spraying arc voltage (S400), the arc phenomenon is imaged by the high-speed video camera 12, and the process of taking the image data into the PC 20 (S500) is performed. Then, using the image data captured in the PC 20, the droplet size / number of sputters and the size / number of spatters are calculated and analyzed (S 600). Using this analysis result, a droplet / sputter determination process (S700) for determining whether the droplet size and the amount of spatter are minimum and optimal (OK) or not (NG) is performed. Do. If the determination result of droplet / sputter is NG in S700, the pulse time is reset (S750). On the other hand, if the determination result of droplet / sputter is OK in S700, the welding completion process (S800) for setting the pulse time is performed on the assumption that the optimum pulse time as the optimum welding condition has been obtained.

  FIG. 6 is a flowchart showing a procedure for determining the size of the droplet, and FIG. 7 is an explanatory diagram of the detection region of the droplet in the captured image. The droplet / sputter calculation / analysis process (S600) will be described below. The size of the droplet 13 in the arc phenomenon varies depending on the wire component and welding conditions. If the size of the droplet 13 is increased, the droplet is not separated normally and causes spattering. Therefore, it is important to quantitatively grasp the size of the droplet 13. In order to determine the droplet size, first, a detection region in the captured image is set (S610). As shown in FIG. 7, a detection area DA is set between the tip of the wire 1 and the base material 2 in the image 30. The detection area DA is preset based on the arc generation position. The image in the detection area DA is binarized (S615), and the boundary between the bright part and the dark part in the image on the horizontal line from the left and right ends of the detection area toward the center is detected (S620). This is done by sampling at a number of points in the vertical direction of the detection area. The distance between the boundary obtained by the left side portion of the droplet 13 in the image and the boundary obtained by the right side portion of the droplet 13 is calculated and recorded (S625). The break of the droplet 13 is detected from the calculation result of the distance between the boundaries (S630). In the detection of the break, it is determined that there is a break when the distance between the boundaries becomes zero. The maximum value of the distance between the boundaries at points obtained by sampling a large number of samples in the horizontal direction is determined as the size of the droplet 13. (S635) Although detailed steps are omitted, in this process, the determination of breaks is sequentially repeated for each image, and when it is determined that there is a break, the size of the droplet 13 is calculated for the image. Yes.

  According to the above procedure, every time the droplets 13 are detached at a predetermined sampling time, all the droplets 13 are numbered to determine the droplet size. And the state of a droplet can be grasped | ascertained quantitatively by calculating | requiring the average value of all the measured droplet sizes.

  FIG. 8 is a flowchart of a method for obtaining the amount of spatter generation, FIG. 9 is an explanatory view of an image used for analyzing the amount of spatter generation, (a) shows a state in which detection lines are set on the captured image, b) is a luminance distribution image, and (c) is a binarized image after image processing of the luminance distribution of (b). The technique for obtaining the amount of spatter generation is as follows. First, as shown in FIG. 9A, detection lines DL are set on both sides of the wire 1 of the image 31 (S650). The detection line DL is set in advance from the arc generation position. In this process, the number and size of spatters are determined by detecting spatter passing through the detection line DL. First, the luminance distribution on the detection line DL is recorded for each predetermined number of images (S655). Next, as shown in FIG. 9B, the recorded luminance distribution is reconstructed as a luminance change image 32 in which the horizontal axis represents the number of images and the vertical axis represents the position of the detection line. As a result of the reconstruction, the vertical axis can be regarded as the detection line DL, and the horizontal axis can be regarded as the time change, and the spatter that has passed over the detection line DL can be expressed. Note that the luminance change image 32 has a density change due to the generation of fume, and therefore it is necessary to exclude this influence. Therefore, filter processing (high-pass filter processing) is performed on the luminance change image (S660). Further, by binarizing the filtered luminance change image with a certain threshold value (S665), a binary image 33 as shown in FIG. 9C is obtained. The isolated points in the binary image are distinguished one by one (S670), and the number and size (area) of the isolated points are obtained (S675). Then, each isolated point is set to a value having a correlation with the number of sputters and the sputter amount (S680).

FIG. 10 is a graph showing the relationship between the pulse time and the droplet size or spatter amount. As shown in FIG. 10, in pulse arc welding, there is a pulse time (optimum pulse time) at which both the droplet size and the spatter amount are minimized. The droplet / sputter determination process (S700) shown in FIG. 2 is a process for determining the optimum pulse time. Hereinafter, the droplet / sputter determination process (S700) and the pulse time resetting process (S750) will be described in detail using specific examples. In the following description, it is assumed that the droplet times and the pulse times at which the spatter amount is minimized are the same. Accordingly, although both the droplet size and the spatter amount are calculated, the pulse time Tp is set based on only the minimum droplet size. Table 2 shows the image analysis result of the arc phenomenon when YGW12 (DS1A): [JIS symbol (brand)] is used as the base material, and FIG. 11 shows the relationship between the pulse time and droplet size in Table 2. It is a graph which shows.

  First, as shown in FIG. 11, the droplet sizes of the respective pulse times are compared using the pulse times of three consecutive points (A1, A2, A3) as a common number. As described in the welding condition setting process (S100), the initial value of the pulse time Tp is 0.6 ms. Accordingly, the droplet sizes under the three conditions of 0.6 ms, 0.7 ms, and 0.8 ms are compared at the start. For example, the droplet size when the pulse time Tp is 0.6 ms is A1, similarly, the droplet size when the pulse time is 0.7 ms is A2, and the droplet size when the pulse time is 0.8 ms is A3. In this case, it is determined whether A1> A2 and A3> A2 are satisfied (OK) or not (NG). If the determination result is OK, 0.7 ms of A2 is the optimum condition.

  If the determination result is NG, the pulse time Tp is increased by 0.1 ms, the number is updated, the droplet size at 0.7 ms is A1, and the droplet size at 0.8 ms is A2. When the droplet size at 0.9 ms is A3, it is determined whether A1> A2 and A3> A2 are satisfied. If the determination result is NG, the pulse time Tp is incremented by 0.1 ms per step in the pulse time resetting process (S750) until the determination result becomes OK, and a series of arcs is determined. The processing from voltage sampling (S300) to droplet / sputter analysis processing (S600) and droplet / sputter determination processing (S700) is repeated.

  If the determination in S700 is OK, the pulse time of A2 at that time is set as the optimal pulse time, and welding (preliminary welding) is completed. According to the data shown in Table 2 and FIG. 11, the pulse time (optimum pulse time) at which the droplet size and the amount of spatter are minimized is 1.5 ms.

  As described above, if the spraying arc voltage and the optimum pulse time are obtained by performing the welding evaluation method including the processing steps of S100 to S800 shown in FIG. 2, actual welding is performed using the welding conditions. By performing the work, highly reliable pulse arc welding can be performed.

  Moreover, since the above evaluation method can be carried out in a short time, every time the type of the base material or the type of wire is changed, a short preliminary welding is performed before the actual welding to obtain an appropriate welding condition. By performing the main welding using the obtained welding conditions, pulse arc welding on various base materials and wires can be easily performed in a short time.

  In the above embodiment, when image processing of arc image data is performed, the relationship between the droplet size and the pulse time and the relationship between the spatter amount and the pulse time are obtained, and the occurrence state of both the droplet and the spatter is determined. However, according to the present invention, it is only necessary to analyze either the state of occurrence of droplets or the state of occurrence of spatter. In other words, the relationship between the droplet size and the pulse time is obtained to analyze only the state of occurrence of the droplet, the quality of the welding state may be determined, or the relationship between the amount of spatter and the pulse time is determined, Only the state of occurrence of spatter may be analyzed to determine whether the welding state is good or bad.

  In particular, it is important to determine the pulse time by analyzing the occurrence of sputtering. Analyzing the spatter generation status is more accurate than analyzing the droplet size because spatter generation is a phenomenon that directly leads to poor welding. There is an advantage that it is possible to discriminate a high welding state.

  Further, in the above embodiment, when the relationship between the droplet size and the pulse time and the relationship between the total amount of sputtering and the pulse time are seen as shown in FIG. In the relationship between the droplet size and the pulse time, and the relationship between the total amount of sputtering and the pulse time, the pulse time that is the minimum of the two may be different. In that case, a short pulse time is selected by comparing both pulse times. The reason is that in the actual welding operation, the shorter the pulse time, the shorter the arc length can be set, and the droplets do not fluctuate and come off smoothly.

It is a block diagram which shows the outline of one Example of a pulse arc welding apparatus. It is a flowchart which shows the procedure of the evaluation method of pulse arc welding. It is explanatory drawing which shows the pulse waveform of welding current. (A)-(c) is explanatory drawing which shows the form of the droplet in each point of (a), (b), (c) of the pulse waveform of FIG. It is a graph which shows the relationship between an arc voltage and the frequency | count of a short circuit. It is a flowchart which shows the process for determining the size of a droplet. It is explanatory drawing of the droplet detection area | region of the captured image used in the process of FIG. It is a flowchart which shows the method for obtaining the parameter | index of spatter generation amount. It is explanatory drawing of the image used for the analysis of spatter generation amount, (a) shows the state which set the detection line to the imaged image, (b) is a brightness distribution image, (c) is the brightness | luminance of (b). It is a binarized image after image processing of the distribution. It is a graph which shows the relationship between a pulse time, the size of a droplet, or a sputter | spatter amount. It is a graph which shows the relationship between the pulse time of Table 2, and droplet size. It is a graph which shows the relationship between an arc voltage and time.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wire 1a Wire tip 2 Base material 3 Welding power source 4 Welding torch 20 Personal computer (PC)
21 Control program for welding power source 22 Arc voltage calculation processing program 23 Droplet size / spatter amount analysis program 24 Arc quality determination program 25 High-speed video camera control program 31 Image 32 Brightness change image 33 Binary image 100 Pulse arc welding equipment Ip peak current value Ib base current value Tp pulse time DA detection area DL detection line

Claims (4)

In the pulse arc welding method of performing arc welding by applying a voltage from the welding power source to the wire and the base material,
Using a high-speed video camera, image the arc at an imaging speed of at least the number of frames / second faster than the frequency of the pulse current to obtain image data,
Perform image processing of the image data of the arc, and analyze at least one of the transition state of the droplets or the occurrence of spatter,
Use the analysis results to determine the quality of the welding state and perform feedback control to set the optimal pulse time to obtain the optimal welding state,
A pulse arc welding method, wherein welding is performed using the optimum pulse time.   The analysis of the transition state of the droplet or the occurrence state of spatter is to determine the relationship between the droplet size and the pulse time or the relationship between the amount of spatter and the pulse time. Pulse arc welding method. A welding power source capable of applying a voltage for generating an arc between the wire and the base material;
A high-speed video camera having an imaging capability of at least the number of frames / second faster than the frequency of the pulse current and capturing the image data by imaging the arc;
Image analysis means for processing image data picked up by the high-speed video camera and analyzing at least one of the transition state of the droplets or the occurrence state of spatter;
The quality determination means for determining the quality of the welding situation using the analysis result of the image analysis means, and setting the optimal pulse time for performing the feedback control and obtaining the optimum welding situation;
Welding power source control means for controlling the voltage applied by the welding power source to the optimum pulse time;
A pulse arc welding apparatus comprising:   4. The pulse arc welding apparatus according to claim 3, further comprising an arc voltage setting means for sampling the arc voltage and automatically setting the spraying arc voltage by feeding back the sampled arc voltage.