JP2012091221A - Arc start quality determination method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an arc start quality determination method capable of properly understanding a tendency of occurrence of failure at the time of arc start.SOLUTION: The arc start quality determination method is related to a consumable electrode gas shield arc welding. In a plurality of times of welding, the number of times of good start and the number of times of respective kinds at occurrence of failure are automatically accumulated on the basis of the result of quality determination at each arc start and the result of determination for kind of failure at occurrence of failure. Owing to this configuration, by setting a certain welding condition, it is quantitatively understood that what kind of failure occurs at what rate under the welding condition by, for example, display of teach pendant TP.

Description

  The present invention relates to a method for determining the quality of arc start in consumable electrode gas shielded arc welding, and more particularly, to a method for automatically determining the quality of arc start based on a welding voltage / current waveform.

  In consumable electrode gas shielded arc welding, arc start is a transient phenomenon, and a defective state is likely to occur compared to a steady welding state. It is important to determine what kind of defect occurs in the arc start or whether it is in a good state in order to perform appropriate welding. Patent Document 1 discloses a method for automatically performing an arc start quality determination method. In this determination method, the pass / fail is determined by comparing the number of long-term short circuits, the number of long-term arc breaks, and the variation in the welding voltage moving average value with a predetermined reference value.

  However, in order to always perform appropriate welding, it is important to reduce the defective state at the arc start. Moreover, a defective state at the arc start does not always occur every time even if welding is performed under exactly the same conditions. In the quality determination method disclosed in Patent Document 1, it is only possible to grasp what kind of defect occurs in a single welding. When welding is repeated under the same conditions, it is impossible to grasp what other defects may occur. In such a case, it has been difficult to effectively perform a treatment for always performing appropriate welding.

JP 2003-326361 A

  The present invention has been conceived under the circumstances described above, and it is an object of the present invention to provide an arc start pass / fail judgment method capable of appropriately grasping the tendency of occurrence of defects in arc start. .

  The arc start pass / fail judgment method provided by the present invention is an arc start pass / fail judgment method in consumable electrode gas shield arc welding. Based on the result of defect type determination, the number of good starts and the number of each type in the case of a defect are automatically accumulated.

  In a preferred embodiment of the present invention, in the determination of the type of failure, the number of long-term short circuits, the number of long-time arc breaks, and the variation value of the welding voltage moving average value during a predetermined determination period from the start of arc start. And the type of the defect is determined based on the number of long-term short circuits, the number of long-time arc breaks, and the variation value of the welding voltage moving average value.

  In a more preferred embodiment of the present invention, in the defect type determination, the number of occurrences of a long-term arc period that lasts longer than a predetermined long-term arc period determination value in a predetermined determination period from the arc start start time is determined. The defect type is determined also by the calculation and the number of occurrences of the long arc period.

  In a more preferred embodiment of the present invention, in the determination of the type of the defect, a medium-term arc period discriminating value shorter than the long-term arc period discriminating value set in advance in a predetermined determination period from the arc start start time is used. The number of occurrences of the intermediate arc period that lasts for a long time is calculated, and the type of defect is determined based on the number of occurrences of the intermediate arc period.

  In a more preferred embodiment of the present invention, in the defect type determination, an initial long-term short-circuit occurrence in which a short-circuit is continued for a time longer than a predetermined time from the start point of the arc start is detected. The defect type is determined.

  In a preferred embodiment of the present invention, there is provided a welding parameter automatic adjustment mode for automatically adjusting welding parameters when the occurrence ratio of the defect exceeds a predetermined reference ratio.

  According to such a configuration, when the welding is repeated, the arc start pass / fail judgment results are automatically accumulated. Therefore, if a person who performs welding sets a certain welding condition, it is possible to quantitatively grasp what kind of defect occurs at what ratio in the welding condition.

  Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

It is a block diagram of the welding apparatus which concerns on this invention. It is a voltage waveform diagram which shows the arc start quality determination method which concerns on this invention. It is a block diagram of the arc monitor device concerning the present invention. It is a block diagram of a variation value calculation circuit according to the present invention. It is a flowchart which shows the determination process of the quality of the arc start which concerns on this invention. It is a block diagram which shows the determination memory | storage device which concerns on this invention. It is a figure which shows the example of a display screen in a teach pendant. It is a voltage and current waveform diagram for demonstrating the arc start quality determination method containing an additional item. It is a block diagram of the arc monitor apparatus for performing an additional item. It is a figure which shows the example of a display screen in the teach pendant containing an additional item.

  Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the drawings.

  FIG. 1 shows an example of a consumable electrode gas shield arc welding apparatus. The welding apparatus A of the present embodiment includes a welding power supply device PS, a voltage detector VD, a current detector ID, an arc monitor device AM, a determination storage device JM, a welding torch 4, and a feed roll 5.

  The welding torch 4 is for inserting the welding wire 1 and for guiding the welding wire 1 to the welding location of the base material 2. The welding torch 4 has a power feed tip 4a. The welding wire 1 slides on the power feed tip 4a. The feed roll 5 feeds the welding wire 1 and is driven by a wire feed motor WM.

  The welding power supply device PS outputs a welding voltage Vw and a welding current Iw. The positive pole of the welding power source device PS is connected to the power feed tip 4 a, and the negative pole is connected to the base material 2. Thereby, an arc 3 is generated between the welding wire 1 and the base material 2. Further, a feed control signal Fc is sent from the welding power supply device PS to the wire feed motor WM. The feed control signal Fc is a signal for controlling the feed of the welding wire 1.

  FIG. 2 is a voltage waveform diagram when the arc start by the welding apparatus A is in a defective state. FIG. 4A shows the time change of the welding voltage Vw, and FIG. 4B shows the time change of the moving average value Vra of the welding voltage. In the welding apparatus A, the following three items are determined by an arc monitor apparatus AM configured as described later.

(1) Number of long-term short circuits Ns
As shown in FIG. 5A, the welding voltage Vw is compared with a predetermined short-circuit determination value Vt1, and the time when Vw ≦ Vt1 is determined as the short-circuit period Ts. And when this short circuit period Ts is longer than the predetermined long-term short circuit discrimination value Tst, it discriminate | determines as a long-term short circuit. The number Ns of times that the above-described long-term short-circuit has occurred during the predetermined determination period Tj from the arc start start time at time t1 is counted. The determination period Tj is set to about several seconds, which is the time for the arc start to converge to a steady state.

(2) Number of long-term arc breaks Nn
As shown in FIG. 5A, the welding voltage Vw is compared with a predetermined arc break discriminating value Vt2, and the arc break period Tn is determined when Vw ≧ Vt2. Then, when the arc break period Tn is longer than a predetermined long-term arc break discriminating value Tnt, it is determined as a long-term arc break, and the number Nn of occurrences of the long-term arc break during the determination period Tj is counted.

(3) Dispersion value Bd of welding voltage moving average value Vra
The welding voltage moving average value Vra shown in FIG. 6B is obtained by calculating the moving average value of the welding voltage Vw shown in FIG. The moving average period corresponding to the time constant during smoothing is shorter than the determination period Tj (several s) and is set to about 10 ms to 200 ms. This is to quantify the irregularities of the short circuit period and the arc period. That is, if the moving average period is too long, it will be smoothed and the irregularity cannot be discriminated. Conversely, if the moving average period is too short, the irregularity will also be discriminated because the fluctuation range is large even if it is not irregular. I can't do that.

  Irregularity between the short-circuit period and the arc period can be determined by the variation value Bd of the welding voltage moving average value Vra. As this variation value Bd, the maximum fluctuation width Wpp of the welding voltage moving average value Vra can be adopted as shown in FIG. Furthermore, the out-of-range time total value Stv obtained by adding the out-of-range time Tvr in which the welding voltage moving average value Vra is outside the predetermined moving average value appropriate range Wvr during the determination period Tj may be employed.

  Whether the arc start is good or bad can be determined based on (1) the number Ns of long-term short circuits, (2) the number Nn of long-term arc breaks, and (3) the variation value Bd of the welding voltage moving average value Vra. The determination criterion changes depending on various welding conditions. For example, when Ns ≧ 3, Nn ≧ 2, and Wpp ≧ 4V in the determination period Tj = 3 s, it can be determined that the arc start is defective.

  In order to realize such a determination, the following configuration is applied to the welding apparatus A.

  As shown in FIG. 1, the voltage detector VD detects the welding voltage Vw and outputs a voltage detection signal Vd. The current detector ID detects the welding current Iw and outputs a current detection signal Id.

  The arc monitor device AM has the configuration shown in FIG. A voltage detection signal Vd and a current detection signal Id are input to the arc monitor device AM. The determination period timer circuit TJ receives the current detection signal Id and outputs a determination period signal Tj. The determination period signal Tj is at a high level for a predetermined time from an arc start start time when the welding wire 1 comes into contact with the base material 2 and the welding current Iw starts energization.

  The first comparison circuit CP1 compares the voltage detection signal Vd with a predetermined short-circuit determination value Vt1, and outputs a short-circuit period signal Ts that becomes a high level when Vd ≦ Vt1. The second comparison circuit CP2 compares the short-circuit period signal Ts with a predetermined long-term short-circuit determination value Tst, and outputs a long-term short-circuit period signal LTs that becomes a High level when Ts ≧ Tst. The long-term short-circuit number counting circuit NS counts the number of times that the long-term short-circuit period signal LTs changes from the Low level to the High level while the determination period signal Tj is at the High level, and outputs the long-term short-circuit number signal Ns.

  The third comparison circuit CP3 compares the voltage detection signal Vd with a predetermined arc break discriminating value Vt2, and outputs an arc break period signal Tn that becomes a high level when Vd ≧ Vt2. The fourth comparison circuit CP4 compares the arc interruption period signal Tn with a predetermined long-term arc interruption judgment value Tnt, and outputs a long-term arc interruption period signal LTn that is at a high level when Tn ≧ Tnt. The long-term arc break occurrence number counting circuit NN counts the number of times the long-term arc break period signal LTn changes from the Low level to the High level while the determination period signal Tj is at the High level, and counts the long-term arc break occurrence number signal Nn. Is output.

  The welding voltage moving average value calculation circuit VRA receives the voltage detection signal Vd, calculates a moving average value during a predetermined moving average period Tra, and outputs a welding voltage moving average value signal Vra. The variation value calculation circuit BD receives the welding voltage moving average value signal Vra as an input, and outputs a variation value signal Bd such as the maximum fluctuation range Wpp and the out-of-range time total value Stv shown in FIG.

  The arc start determination circuit ASJ receives the long-term short circuit number signal Ns, the long-term arc break occurrence number signal Nn, and the variation value signal Bd, and determines whether or not the arc start is good according to a predetermined criterion.

  FIG. 4 is a block diagram of the variation value calculation circuit BD when calculating the out-of-range time total value Stv. The fifth comparison circuit CP5 compares the welding voltage moving average value signal Vra with a predetermined moving average value appropriate range Wvr, and outputs an out-of-range time signal Tvr that is at a high level when out of the range. The summing circuit SUM sums the out-of-range time signal Tvr while the determination period signal Tj is at the High level, and outputs the out-of-range time sum value signal Stv as the variation value signal Bd.

  FIG. 5 is a flowchart showing a process for determining whether the arc start is good or bad by the arc start determination circuit ASJ. The figure is an example of the determination process. Hereinafter, a description will be given with reference to FIG.

  In step ST1, the long-term short-circuit number Ns is equal to or greater than a predetermined reference number Nst, and the out-of-range time total value Stv is equal to or greater than a predetermined first reference time Tt1 and less than a predetermined second reference time Tt2. It is determined whether the number of long-term arc break occurrences Nn is equal to or greater than a predetermined reference number Nnt. If YES, the process proceeds to step ST2, and the arc start is determined to be “slightly bad”. If NO, the process proceeds to step ST3. move on.

  In step ST3, it is determined whether the out-of-range time total value Stv is equal to or greater than the second reference time Tt2. If YES, the process proceeds to step ST4, where the arc start is determined as “bad”, and if NO, “good”. Is determined. The arc start determination circuit ASJ outputs the determination result as a determination result signal Asj.

  FIG. 6 shows the configuration of the determination storage device JM of the welding apparatus A. The determination storage device JM includes a determination accumulation circuit JA, a welding condition setting circuit WC, and a welding parameter adjustment circuit TG.

  The welding condition setting circuit WC sets a welding voltage Vw, a welding current Iw, and a welding speed WV, and sends these pieces of information as a welding condition setting signal Wc to the welding power supply device PS. The welding condition setting signal Wc is also sent to the welding parameter adjustment circuit TG and the determination accumulation circuit JA. The welding condition setting circuit WC may be incorporated in a control device for a robot that holds the welding torch 4, for example.

  Determination accumulating circuit JA receives determination result signal Asj from arc monitor device AM. The determination result signal Asj is information indicating whether the arc start of the welding subjected to the determination is good or defective, and if it is defective, the type is (1) to (3) described above. Contains. The judgment accumulating circuit JA holds the normal start number Cr0, the long-term short-circuit occurrence start number Cr1, the long-term arc break occurrence start number Cr2, and the voltage variation occurrence start number Cr3 as variables. Based on the determination result signal Asj, the determination accumulating circuit JA adds 1 to the normal start number Cr0 when the arc start of the target welding is good, and generates a long-term short circuit when there is a short circuit failure. 1 is added to the number of start times Cr1, and 1 is added to the number of start times Cr2 of long-term arc break occurrence if the start failure is long-term arc break occurrence. Add 1 to Cr3.

  Next, the determination accumulating circuit JA uses the accumulated normal start count Cr0, long-term short-circuit occurrence start count Cr1, long-term arc break occurrence start count Cr2, and voltage variation occurrence start count Cr3, for example, as a teaching connected to the determination storage device JM. Send to pendant TP. In this case, the determination accumulating circuit JA may be incorporated in, for example, a robot control device that holds the welding torch 4. As shown in FIG. 7, a determination result accumulation screen is displayed on the teach pendant TP. This screen displays the cumulative number of normal start, long-term short-circuit occurrence start, long-term arc break-off occurrence start, and voltage variation occurrence start.

  Further, the determination accumulating circuit JA holds a long-term short-circuit occurrence start reference ratio Cs1, a long-term arc break occurrence start reference ratio Cs2, and a voltage variation occurrence start reference ratio Cs3. The long-term short-circuit occurrence start reference ratio Cs1, the long-term arc breakage start reference ratio Cs2, and the voltage variation occurrence start reference ratio Cs3 are ratios determined in advance by the user. It is a size that seems to be allowed as a ratio. The judgment accumulating circuit JA has a normal start count Cr0, a long-term short-circuit occurrence start count Cr1, a long-term arc break occurrence start count Cr2, and a voltage variation occurrence start count Cr3. Each ratio of the voltage variation start is calculated. Then, it is determined whether or not each ratio exceeds the long-term short-circuit occurrence start reference ratio Cs1, the long-term arc break occurrence start reference ratio Cs2, and the voltage variation occurrence start reference ratio Cs3. When any ratio exceeds the long-term short-circuit occurrence start reference ratio Cs1, the long-term arc break occurrence start reference ratio Cs2, and the voltage variation occurrence start reference ratio Cs3, for example, in the determination result accumulation screen shown in FIG. Is highlighted. If the user touches a predetermined icon (not shown) while this highlighting is performed, guidance for suppressing arc start failure of the corresponding item is displayed. In addition, it is good also as a structure which does not perform ratio comparison with long-term short circuit generation | occurrence | production start reference | standard ratio Cs1, long-term arc break generation | occurrence | production start reference ratio Cs2, and voltage variation generation | occurrence | production start reference ratio Cs3 until it exceeds the predetermined number of times of cumulative welding.

  The normal start count Cr0, long-term short-circuit occurrence start count Cr1, long-term arc break occurrence start count Cr2 and voltage variation occurrence start count Cr3 are accumulated for each group of welding conditions determined to be similar or similar. For example, the determination accumulating circuit JA holds a welding condition group determined by set values of the welding current Iw, the welding voltage Vw, and the welding speed WV. When the setting range of the welding current Iw is 0 to 400A, the welding current Iw is divided every 50A. When the setting range of the welding voltage Vw is 10 to 50V, the welding voltage Vw is divided every 5V. When the setting range of the welding speed WV is 0 to 250 cm / min, it is classified every 50 cm / min. Accordingly, when the welding condition is determined in the welding condition setting circuit WC, the cumulative result of the welding condition group corresponding to the welding condition (welding current Iw, welding voltage Vw, welding speed WV) is displayed on the teach pendant TP.

  Further, the determination accumulating circuit JA sends the ratio comparison results of the long-term short-circuit occurrence start reference ratio Cs1, the long-term arc break occurrence start reference ratio Cs2, and the voltage variation occurrence start reference ratio Cs3 to the welding parameter adjustment circuit TG as a determination accumulated signal Ja. send.

  A welding condition setting signal Wc and a determination accumulation signal Ja are input to the welding parameter adjustment circuit TG. The welding parameter adjusting circuit TG welds the welding power source device PS to the welding power source device PS when there are items exceeding the long-term short-circuit occurrence start reference ratio Cs1, the long-term arc breakage start reference ratio Cs2, and the voltage variation occurrence start reference ratio Cs3. A parameter adjustment signal Tg is sent. When the welding parameter adjustment signal Tg is sent, the welding apparatus A takes a welding parameter automatic adjustment mode.

  The welding parameter automatic adjustment mode will be described by taking as an example a case where the ratio of long-term short-circuit occurrence start exceeds the long-term short-circuit occurrence start reference ratio Cs1 because the number of long-term short-circuit occurrence start times Cr1 is relatively large. The cause of the occurrence of a short-circuit short-circuit start failure is that the rate of increase in the short-circuit current when a droplet grown in the arc is short-circuited is small. When the rate of increase in the short-circuit current is small, the pinch force for the short-circuited droplet is insufficient, and the droplet does not separate from the base material 2. This delays the re-ignition of the arc. If this short circuit time becomes long, the welding wire 1 will rush into the molten pool and cause the melting balance to be lost. For this reason, it is effective to increase the increase rate of the short-circuit current in order to suppress the failure of the long-term short-circuit occurrence start. As a measure for this, it has been found by the inventors' tests that reducing the electronic reactor value is effective.

  Therefore, the welding parameter adjustment circuit TG instructs the welding power supply device PS by the welding parameter adjustment signal Tg so as to decrease the electronic reactor value at a constant rate. By this instruction, in the welding power source apparatus PS, the electronic reactor value is set to be small at a constant rate. Subsequent welding is repeated with the parameters in this state. As a result, when the ratio of the long-term short-circuit occurrence start ratio does not exceed the long-term short-circuit occurrence start reference ratio Cs1, the welding parameter automatic adjustment mode is completed. On the other hand, if the ratio of the long-term short-circuit occurrence start ratio exceeds the long-term short-circuit occurrence start reference ratio Cs1, the welding parameter adjustment circuit TG instructs the welding power source apparatus PS to further reduce the electronic reactor value. Send. By repeating this, the long-term short-circuit occurrence start frequency Cr1 is suppressed.

  The adjustment of the welding parameters may be performed manually according to the judgment of the user, in addition to the case of using the automatic welding parameter adjustment mode. For example, the ratio of the long-term short-circuit occurrence start does not exceed the long-term short-circuit occurrence start reference ratio Cs1, but when the long-term short-circuit occurrence start number Cr1 is relatively large, for example, the electronic reactor value is adjusted at the user's judgment. .

  Next, the operation of the arc start pass / fail judgment method of this embodiment will be described.

  According to the present embodiment, when welding is repeatedly performed, the arc start pass / fail determination results are automatically accumulated. The repetition of this welding may be a test welding whose main purpose is to determine whether the arc start is good or not, or an actual welding. Regardless of what kind of welding is performed, the results are classified according to welding conditions such as the welding current Iw, the welding voltage Vw, and the welding speed WV, and the arc start pass / fail judgment results are accumulated. Accordingly, when a user of the welding apparatus A sets a certain welding condition, the display of the teach pendant TP quantitatively grasps what kind of defect occurs at what ratio in the welding condition. It is possible.

  According to the welding parameter automatic adjustment mode, arc start defects that occur frequently at that time can be automatically suppressed. This adjustment work does not depend on the skill level of the user. In the above-described example, when the ratio of the long-term short-circuit occurrence start is high, the electronic reactor value is reduced. In the welding parameter automatic adjustment mode according to the present invention, welding that is assumed for various arc start failures is assumed. Parameter adjustment can be set as appropriate.

  Hereinafter, the case where the arc start quality determination method is performed for additional items in the welding apparatus A will be described. In the following description, the same or similar elements as those in the above embodiment are denoted by the same reference numerals as those in the above embodiment.

  FIG. 8 is a voltage waveform diagram and a current waveform diagram at the arc start by the welding apparatus A. FIG. 6A shows a time change of the welding voltage Vw in a simplified manner, and FIG. 4B shows a time change of the welding current Iw. In addition to the items (1) to (3) described above, the arc monitor device AM determines the following three items.

(4) Number of long-term arc occurrence Na1
As shown in FIG. 8A, a period in which the welding voltage Vw is between the short circuit determination value Vt1 and the arc break determination value Vt2 is determined as an arc period Ta. And when this arc period Ta is longer than the predetermined long-term arc period discriminating value Tat1, it is discriminated as a long-term arc. The number Na1 of occurrence of the long-term arc is counted during the determination period Tj.

(5) Number of occurrences of medium-term arc Na2
When the arc period Ta is shorter than the predetermined long-term arc period discriminant value Tat1 and longer than the medium-term arc period discriminant value Tat2, it is discriminated as a medium-term arc. The number Na2 of occurrences of the medium-term arc during the above-described determination period Tj is counted.

(6) Initial long-term short circuit occurrence Ss
As shown in FIG. 8B, the short-circuit period that occurs immediately after the welding current Iw starts energization is determined as the initial short-circuit period Tss. When the initial short circuit period Tss is longer than a predetermined initial short circuit period determination value Tss1, it is determined as the initial long-term short circuit occurrence Ss.

  When the arc period Ta is long, there is a high possibility that a welding defect such as a defect in the appearance of the weld bead will occur. In such a case, items of (4) long-term arc occurrence frequency Na1 and (5) medium-term arc occurrence frequency Na2 are added to the above-described arc start quality determination method.

  When the initial short-circuit period Tss is long, there is a high possibility that the arc 3 does not start from the start of welding and the short-circuit continues and a problem occurs that the beat start end portion is defective. On the other hand, when the short-circuit period Ts is prolonged, the bead tends to be thinned. Therefore, when the initial short-circuit period Tss is long, it may be desirable to make a determination separately from the case where the short-circuit period Ts is long. In such a case, the item of (6) initial long-term short-circuit occurrence Ss is added to the above-described arc start quality determination method.

  By adding not only the items (1) to (3) described above, but also (4) long-term arc occurrence frequency Na1, (5) medium-term arc occurrence frequency Na2, and (6) initial long-term short-circuit occurrence Ss. An arc start pass / fail judgment can be made. For example, when the long-term short-circuit determination value Tst is 10 ms, the arc period Ta is 80 ms and the short-circuit period immediately after is 3 ms. In this case, the arc period Ta is too long, and there is a high possibility that the appearance defect of the weld bead will occur. However, when the determination is made only with the items (1) to (3), it is not determined as defective. The long-term arc period discriminant value Tat1 is set to 60 ms, the medium-term arc period discriminant value Tat2 is set to 40 ms, and (4) the long-term arc occurrence number Na1 and (5) the medium-term arc occurrence number Na2 are added to the judgment items, and this case is also detected as defective. Can do.

  In order to realize such a determination, the arc monitor device AM has the configuration shown in FIG. A voltage detection signal Vd and a current detection signal Id are input to the arc monitor device AM.

  The arc period determination circuit TA receives the short-circuit period signal Ts and the arc break period signal Tn, and outputs an arc period signal Ta that is at a high level only while both are at a low level. The sixth comparison circuit CP6 receives the arc period signal Ta and measures the time during which the arc period signal Ta is at the high level. The sixth comparison circuit CP6 outputs a long-term arc signal LTa1 that is at a high level after the measurement time exceeds a predetermined long-term arc period determination value Tat1 until the arc-period signal Ta switches to a low level. The long-term arc occurrence number counting circuit NA1 counts the number of times the long-term arc signal LTa1 changes from the Low level to the High level while the determination period signal Tj is at the High level, and outputs the long-term arc occurrence number signal Na1.

  The seventh comparison circuit CP7 receives the arc period signal Ta and measures the time during which the arc period signal Ta is at the high level. The seventh comparison circuit CP7 outputs a medium-term arc signal LTa2 that is at a high level after the measurement time exceeds a predetermined medium-term arc period determination value Tat2 until the arc-period signal Ta is switched. The medium period arc occurrence number counting circuit NA2 counts the number of times the medium period arc signal LTa2 changes from the low level to the high level while the determination period signal Tj is at the high level. Further, the medium-term arc occurrence number counting circuit NA2 receives the long-term arc occurrence number signal Na1, calculates a value obtained by subtracting the long-term arc occurrence number from the counted number, and outputs a medium-term arc occurrence number signal Na2.

  The initial long-term short-circuit detection circuit SS is at a high level when the initial short-circuit period Tss from when the determination period signal Tj becomes high level until the current detection signal Id starts decreasing exceeds a predetermined initial short-circuit period determination value Tss1. The initial long-term short-circuit occurrence signal Ss is output. The initial long-term short circuit occurrence signal Ss is switched to the Low level when the determination period signal Tj becomes the Low level.

  In addition to the long-term short-circuit number signal Ns, the long-term arc break occurrence number signal Nn, and the variation value signal Bd, the arc start determination circuit ASJ includes a long-term arc occurrence number signal Na1, a medium-term arc occurrence number signal Na2, and an initial long-term short-circuit occurrence signal Ss. As an input, whether the arc start is good or bad is determined according to a predetermined criterion.

  When the process in FIG. 5 is performed under the condition of Tst ≧ Tss1, the initial short circuit period Tss is included in the long-term short circuit number Ns. When the initial long-term short-occurrence signal Ss is at a high level, a more strict pass / fail judgment can be made by comparing the reference number Nst with a predetermined number using the number obtained by subtracting 1 from the long-term short-circuit number Ns. .

  The arc start determination circuit ASJ determines “defective” when the initial long-term short-circuit occurrence signal Ss becomes High level. Even when the long-time arc occurrence number Na1 is equal to or greater than a predetermined reference number, it is determined as “bad”. When the number of long-term arc occurrences Na1 is equal to or less than a predetermined reference number and the number of medium-term arc occurrences is equal to or greater than a predetermined reference number, it is determined as “slightly defective”.

  In addition to the above-described configuration, the determination accumulating circuit JA holds the long-term arc occurrence start count Cr4, the medium-term arc occurrence start count Cr5, and the initial long-term short-circuit occurrence start count Cr6 as variables. Based on the determination result signal Asj, the determination accumulating circuit JA adds 1 to the normal start number Cr0 when the arc start of the target welding is good, and when it is defective due to long-term arc generation, 1 is added to the long-term arc generation start number Cr4, and 1 is added to the medium-term arc generation start number Cr5 when the start failure is caused by the medium-term arc generation. 1 is added to the short-circuit occurrence start count Cr6.

  Next, the judgment accumulating circuit JA also sends the accumulated long-term arc generation start number Cr4, medium-term arc generation start number Cr5, and initial long-term short-circuit generation start number Cr6 to the teach pendant TP. As shown in FIG. 10, these times are also displayed on the determination result accumulation screen displayed by the teach pendant TP.

  The determination accumulating circuit JA further holds a long-term arc occurrence start reference ratio Cs4, a medium-term arc occurrence start reference ratio Cs5, and an initial long-term short-circuit occurrence start reference ratio Cs6. The long-term arc generation start reference ratio Cs4, the medium-term arc generation start reference ratio Cs5, and the initial long-term short-circuit generation start reference ratio Cs6 are ratios determined in advance by the user, and each defective item occupies the cumulative number of welding times so far. It is a size that seems to be allowed as a ratio. The judgment accumulating circuit JA includes a normal start count Cr0, a long-term short-circuit occurrence start count Cr1, a long-term arc break occurrence start count Cr2, a voltage variation occurrence start count Cr3, a long-term arc occurrence start reference count Cr4, a medium-term arc occurrence start reference count Cr5, and From the initial long-term short-circuit occurrence start reference number Cr6, the ratio of each of the long-term short-circuit occurrence start, long-term arc break start, voltage variation occurrence start, long-term arc occurrence start, medium-term arc occurrence start, initial long-term short-circuit occurrence start in the cumulative number of welding calculate. Each ratio is a long-term short-circuit occurrence start reference ratio Cs1, a long-term arc breakage start reference ratio Cs2, a voltage variation occurrence start reference ratio Cs3, a long-term arc occurrence start reference ratio Cs4, a medium-term arc occurrence start reference ratio Cs5, and an initial long-term It is determined whether or not the short circuit occurrence start reference ratio Cs6 is exceeded. When the ratio of any of the long-term arc generation start, the medium-term arc generation start, and the initial long-term short-circuit generation start exceeds the long-term arc generation start reference ratio Cs4, the medium-term arc generation start reference ratio Cs5, and the initial long-term short-circuit generation start reference ratio Cs6, The corresponding item is highlighted on the determination result accumulation screen displayed by the teach pendant TP. If the user touches a predetermined icon (not shown) while this highlighting is performed, guidance for suppressing arc start failure of the corresponding item is displayed. In these items as well, the ratio comparison with the long-term arc generation start reference ratio Cs4, the medium-term arc generation start reference ratio Cs5, and the initial long-term short-circuit generation start reference ratio Cs6 is not performed until the predetermined cumulative number of welding times is exceeded. Also good.

  The accumulation of the long-term arc generation start number Cr4, the medium-term arc generation start number Cr5, and the initial long-term short-circuit generation start number Cr6 is also performed for each group of welding conditions determined to be similar or similar. Further, the determination accumulating circuit JA includes a welding parameter adjusting circuit in addition to the determination accumulating signal Ja and the ratio comparison result between the long-term arc occurrence start reference ratio Cs4, the medium-term arc occurrence start reference ratio Cs5, and the initial long-term short-circuit occurrence start reference ratio Cs6. Send to TG.

  The arc start quality determination method according to the present invention is not limited to the above-described embodiment. The specific configuration of the present invention can be modified in various ways.

DESCRIPTION OF SYMBOLS 1 Welding wire 2 Base material 3 Arc 4 Welding torch 5 Feed roll 5a Feed tip A Welding device AJ Welding state judgment circuit AM Arc monitor device ASJ Arc start judgment circuit Asj Judgment result signal BD Variation value calculation circuit Bd Welding voltage moving average value Vra variation value (signal)
CP1 1st comparison circuit CP2 2nd comparison circuit CP3 3rd comparison circuit CP4 4th comparison circuit CP5 5th comparison circuit CP6 6th comparison circuit CP7 7th comparison circuit Cr0 Normal start frequency Cr1 Long-term short circuit occurrence Start count Cr2 Long-term arc break start count Cr3 Voltage variation occurrence start count Cr4 Long-term arc occurrence start count Cr5 Medium-term arc occurrence start count Cr6 Initial long-term short-circuit start count Cs1 Long-term short-circuit occurrence start reference ratio Cs2 Long-term arc break start start reference ratio Cs3 Voltage variation occurrence start reference ratio Cs4 Long-term arc occurrence start reference ratio Cs5 Medium-term arc occurrence start reference ratio Cs6 Initial long-term short-circuit occurrence start reference ratio Fc Feed control signal ID Current detector Id Current detection signal Iw Welding current JA Product circuit Ja Judgment accumulation signal JM Judgment storage device LTn Long-term arc break period signal LTs Long-term short-circuit period signal LTa1 Long-term arc signal LTa2 Mid-term arc signal NN Long-term arc break occurrence count circuit Nn Long-term arc break occurrence count (signal)
Nnt, Nst Reference count NS Long-term short-circuit count circuit Ns Long-term short-circuit count (signal)
NA1 Long-term arc occurrence count circuit NA2 Mid-term arc occurrence count circuit Na1 Long-term arc occurrence count (signal)
Na2 Number of occurrences of medium-term arc (signal)
PS Welding power supply devices ST1 to 5 Step SUM Summing circuit Stv Out-of-range time summation value (signal)
SS Initial long-term short circuit detection circuit Ss Initial long-term short circuit occurrence (signal)
TA Arc period judgment circuit Ta Arc period (signal)
TG welding parameter adjustment circuit Tg welding parameter adjustment signal TJ determination period timer circuit Tj determination period (signal)
Tn Arc break period (signal)
Tnt Long-term arc break discriminating value Tra Moving average period Ts Short-circuit period (signal)
Tst Long-term short circuit discrimination value Tt1 First reference time Tt2 Second reference time Tvr Out-of-range time (signal)
Tat1 Long-term arc period discriminant value Tat2 Mid-term arc period discriminant value Tss Initial short-circuit period (signal)
Tss1 initial short-circuit period discrimination value VD voltage detector Vd voltage detection signal VRA welding voltage moving average value calculation circuit Vra welding voltage moving average value (signal)
Vt1 Short-circuit determination value Vt2 Arc break determination value Vw Welding voltage WC Welding condition setting circuit Wc Welding condition setting signal Wi Current appropriate range WM Wire feed motor Wpp Maximum fluctuation width WV welding voltage moving average value Welding speed Wv Voltage appropriate range Wvr Movement Average value appropriate range

Claims (6)

An arc start quality determination method in consumable electrode gas shielded arc welding,
In multiple weldings, the number of good starts and the number of each type in the case of failure are automatically determined based on the results of pass / fail judgment at each arc start and failure type determination in case of failure. An arc start pass / fail judgment method characterized by accumulating.   In determining the type of failure, the number of long-term shorts during the predetermined determination period from the start of arc start, the number of long-term arc breaks, and the variation value of the welding voltage moving average value, 2. The arc start quality determination method according to claim 1, wherein the defect type determination is performed based on the number of long-term arc breaks and a variation value of a welding voltage moving average value.   In determining the type of defect, the number of occurrences of a long-term arc period that lasts longer than a predetermined long-term arc period discriminating value during a predetermined determination period from the start of arc start is calculated, and the number of occurrences of the long-term arc period is The arc start quality determination method according to claim 2, wherein the defect type determination is also performed.   In determining the type of defect, the number of occurrences of a medium-term arc period that lasts longer than a predetermined medium-term arc period determination value that is shorter than the predetermined long-term arc period determination value in a predetermined determination period from the start point of the arc start is calculated. 4. The arc start pass / fail determination method according to claim 3, wherein the defect type determination is also performed based on the number of occurrences of the intermediate arc period.   3. The defect type determination includes detecting an initial long-term short circuit occurrence in which a short circuit is continued for a time longer than a predetermined time from the arc start start time, and performing the defect type determination also by the initial long-term short circuit occurrence. The arc start quality determination method according to any one of 4 to 4.   The arc start pass / fail judgment method according to any one of claims 1 to 5, further comprising a welding parameter automatic adjustment mode for automatically adjusting a welding parameter when the occurrence ratio of the defect exceeds a predetermined reference ratio. .

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