JP2014151355A - Arc-welding apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an arc-welding apparatus, in which abnormality in the cable of the apparatus and the connection part of the cable can be determined.SOLUTION: An arc-welding apparatus comprises: a main circuit for supplying an electric power between an electrode and a mother metal; a first cable connected with a first output terminal of the main circuit and the electrode; a second cable connected between a second output terminal of the main circuit and the mother metal; a first detection line for detecting an arc voltage; a second detection line for detecting the arc voltage; a first voltage detection part for detecting the output voltage of the main circuit; a second voltage detection part for detecting the arc voltage; and a comparison part for comparing the voltage detected in the first voltage detection part and the voltage detected in the second voltage detection part. In the case where the difference between the voltage detected in the first voltage detection part and the voltage detected in the second voltage detection part is a predetermined value or more, the comparison part determines that either the first cable or the second cable, or the first detection line or the second detection line is abnormal.

Description

  The present invention relates to detection of an arc voltage detection line used in an arc welding apparatus, a disconnection of a welding output cable, an abnormality of a connection portion thereof, and the like.

  Regarding an arc welding apparatus, a method of obtaining an arc voltage from the vicinity of an arc generation point using an arc voltage detection line is known (for example, see Patent Document 1).

JP 61-007071 A

  By detecting the arc voltage necessary for control from the vicinity of the arc and controlling the arc voltage, welding can be stabilized and high-quality welding can be performed. Moreover, even if a voltage drop occurs in the extension cable by using the extension cable for welding output, the voltage in the vicinity of the arc is detected. Therefore, the detection of the arc voltage is not affected by the extension cable. Voltage control is possible.

  However, the connection between the arc welder and the base metal, or between the arc welder and the arc generation point (for example, the connection between the arc welder and the cable, the connection between the cable and the extension cable, When a connection failure occurs in a case where the connection part is a sliding type), the following problem occurs. For example, when the contact resistance of the connection portion is high, a voltage drop occurs and power is wasted. In addition, when the contact resistance of the connecting portion is remarkably increased, the portion may generate heat and become high temperature. Further, when the control voltage detection line is in a disconnected or semi-disconnected state, the arc voltage cannot be controlled correctly. As a result, there arises a problem that a welding defect is generated, and as a result of performing unstable welding, post-processing work is required.

  In order to solve the above-mentioned problems, an arc welding apparatus according to the present invention is an arc welding apparatus that performs arc welding by supplying electric power between a welding electrode and a base material, the welding electrode and the base material. Between the main circuit part for supplying power between the first output terminal and one of the two output terminals of the main circuit part, and the welding electrode A first cable for supplying power to the side, and a second output terminal which is the other output terminal of the main circuit unit, and for supplying power to the base material side A second cable, a first detection line connected to the side of the welding electrode for detecting an arc voltage in the arc, and a connection to the base material side for detecting the arc voltage in the arc A voltage between the detected second detection line and the output terminal of the main circuit unit 1 voltage detection unit, a second voltage detection unit that is electrically connected to the first detection line and the second detection line and detects an arc voltage, and the first voltage detection unit A comparison unit that compares the voltage detected by the second voltage detection unit with the voltage detected by the second voltage detection unit, and the comparison unit includes a voltage detected by the first voltage detection unit and a voltage detected by the second voltage detection unit. When the difference from the detected voltage is a predetermined value or more, it is determined that the first cable, the second cable, the first detection line, or the second detection line is abnormal. .

  In addition to the above, the arc welding apparatus of the present invention includes a third voltage detection unit for detecting a voltage between the first detection line and the second cable, the first cable, and the first cable. A fourth voltage detection unit for detecting a voltage between the two detection lines, and the comparison unit includes a voltage detected by the first voltage detection unit and a voltage detected by the second voltage detection unit. Based on the voltage detected by the third voltage detector and the voltage detected by the fourth voltage detector, the first cable, the second cable, the first detection line, or the second It is determined that the detection line is abnormal.

  In addition to the above, the arc welding apparatus of the present invention performs constant current control welding, and the comparison unit is configured such that the detection voltage of the third voltage detection unit is the detection voltage of the second voltage detection unit. The detection voltage of the fourth voltage detection unit is higher than the detection voltage of the third voltage detection unit, and the detection voltage of the first voltage detection unit is higher than the detection voltage of the fourth voltage detection unit. If the detection result of the second voltage detection unit is high and the standard voltage value that is the detection result of the second voltage detection unit at the normal time is the same, it is determined that the first cable is abnormal The detection voltage of the fourth voltage detection unit is higher than the detection voltage of the second voltage detection unit, and the detection voltage of the third voltage detection unit is higher than the detection voltage of the fourth voltage detection unit. The detection voltage of the first voltage detection unit is higher than the detection voltage of the third voltage detection unit. And when the detection result of the second voltage detection unit is the same as the standard voltage value, it is determined that the second cable is abnormal, and the detection voltage of the third voltage detection unit is the second voltage The detection voltage of the fourth voltage detection unit is higher than the detection voltage of the voltage detection unit, the detection voltage of the fourth voltage detection unit is higher than the detection voltage of the third voltage detection unit, and the detection voltage of the first voltage detection unit is the fourth voltage detection If the detection voltage of the fourth voltage detection unit is lower than the standard voltage value, it is determined that the first detection line is abnormal, and the fourth voltage detection unit The detection voltage of the second voltage detection unit is higher than the detection voltage of the second voltage detection unit, the detection voltage of the third voltage detection unit is higher than the detection voltage of the fourth voltage detection unit, and the first voltage detection unit Is higher than the detection voltage of the third voltage detector, and the fourth voltage detector If output result is lower than the standard voltage value is the second detection line is determined to be abnormal.

  In addition to the above, in the arc welding apparatus of the present invention, the comparison unit has zero detection voltage of the third voltage detection unit and zero detection voltage of the second voltage detection unit. When the detection voltage is higher than the detection voltage of the third voltage detection unit and the detection voltage of the first voltage detection unit is the same value as the detection voltage of the fourth voltage detection unit, the first cable is It is determined that there is a disconnection, the detection voltage of the fourth voltage detection unit and the detection voltage of the second voltage detection unit are zero, and the detection voltage of the third voltage detection unit is the fourth voltage detection If the detection voltage of the first voltage detection unit is the same value as the detection voltage of the fourth voltage detection unit, it is determined that the second cable is disconnected, The detection voltage of the voltage detection unit 3 and the detection voltage of the second voltage detection unit are zero, and the fourth voltage detection unit When the output voltage is higher than the detection voltage of the third voltage detection unit and the detection voltage of the first voltage detection unit is higher than the detection voltage of the fourth voltage detection unit, the first detection line That the detection voltage of the fourth voltage detection unit and the detection voltage of the second voltage detection unit are zero, and the detection voltage of the third voltage detection unit is the fourth voltage. When the detection voltage of the first voltage detection unit is higher than the detection voltage of the detection unit and higher than the detection voltage of the third voltage detection unit, it is determined that the second detection line is disconnected It is.

  In addition to the above, the arc welding apparatus of the present invention further includes a welding current detection unit that detects a welding current, and the comparison unit includes a voltage detected by the first voltage detection unit and a second voltage detection unit. Based on the detected voltage, the voltage detected by the third voltage detector, the voltage detected by the fourth voltage detector, and the welding current detected by the welding current detector, the first cable or It is determined that the second cable, the first detection line, or the second detection line is abnormal.

  In addition to the above, the arc welding apparatus of the present invention performs constant voltage control welding, and the comparison unit is configured such that the detection voltage of the third voltage detection unit is the detection voltage of the second voltage detection unit. The detection voltage of the fourth voltage detection unit is higher than the detection voltage of the third voltage detection unit, and the detection voltage of the first voltage detection unit is higher than the detection voltage of the fourth voltage detection unit. When the welding current value detected by the welding current detection unit is high and lower than the welding current value in the normal state, it is determined that the first cable is abnormal, and the detected voltage of the fourth voltage detection unit Is higher than the detection voltage of the second voltage detection unit, the detection voltage of the third voltage detection unit is higher than the detection voltage of the fourth voltage detection unit, and the detection voltage of the first voltage detection unit Is higher than the detection voltage of the third voltage detector, and the welding current detector When the detected welding current value is lower than the welding current value in the normal state, it is determined that the second cable is abnormal, and the detection voltage of the third voltage detection unit is detected by the second voltage detection unit. Higher than the voltage, the detection voltage of the fourth voltage detection unit is higher than the detection voltage of the third voltage detection unit, and the detection voltage of the first voltage detection unit is higher than the detection voltage of the fourth voltage detection unit. And the welding current value detected by the welding current detection unit is higher than the welding current value in the normal state, the first detection line is determined to be abnormal, and the fourth voltage detection unit The detection voltage is higher than the detection voltage of the second voltage detection unit, the detection voltage of the third voltage detection unit is higher than the detection voltage of the fourth voltage detection unit, the detection voltage of the first voltage detection unit The detection voltage is higher than the detection voltage of the third voltage detection unit, and the welding current detection is performed. If the welding current detected in parts is higher than the welding current value of the normal state is one in which the second detection line is determined to be abnormal.

  In addition to the above, in the arc welding apparatus of the present invention, the comparison unit has zero detection voltage of the third voltage detection unit and zero detection voltage of the second voltage detection unit. The detected current is higher than the detected voltage of the third voltage detector, the detected voltage of the first voltage detector is equal to or higher than the detected voltage of the fourth voltage detector, and the welding current detected by the welding current detector When the value is zero, it is determined that the first cable is disconnected, the detection voltage of the fourth voltage detection unit and the detection voltage of the second voltage detection unit are zero, and the third voltage detection unit The detection voltage of the voltage detection unit is higher than the detection voltage of the fourth voltage detection unit, the detection voltage of the first voltage detection unit is greater than or equal to the detection voltage of the fourth voltage detection unit, and the welding current detection If the welding current value detected at the part is zero, it is determined that the second cable is disconnected. The detection voltage of the third voltage detection unit and the detection voltage of the second voltage detection unit are zero, the detection voltage of the fourth voltage detection unit is higher than the detection voltage of the third voltage detection unit, When the detection voltage of the first voltage detection unit is higher than the detection voltage of the fourth voltage detection unit and the welding current value detected by the welding current detection unit is not zero, the first detection line is broken. It is determined that the detection voltage of the fourth voltage detection unit and the detection voltage of the second voltage detection unit are zero, and the detection voltage of the third voltage detection unit is equal to that of the fourth voltage detection unit. If the detection voltage of the first voltage detection unit is higher than the detection voltage, the detection voltage of the third voltage detection unit is higher than the detection voltage, and the welding current value detected by the welding current detection unit is not zero, It is determined that the second detection line is disconnected.

  In addition to the above, the arc welding apparatus of the present invention uses the detected voltage as an average value for comparison.

  In addition to the above, the arc welding apparatus of the present invention uses the detected voltage as an effective value for comparison.

  According to the arc welding apparatus of the present invention, the voltage detection using the welding cable connected to the main circuit portion and the voltage detection near the arc using the voltage detection line are individually performed, and based on these voltage detection results. Thus, it is possible to detect that an abnormality has occurred in the welding cable or the voltage detection line, and to recognize which path has the abnormality. By detecting an abnormality and stopping the output of the device, accidents and device damage can be prevented in advance, and damage can be reduced.

The figure which shows schematic structure of the arc welding apparatus in Embodiment 1 of this invention. The figure for demonstrating the voltage detection in the normal time in Embodiment 1 of this invention The figure for demonstrating voltage detection when abnormality has generate | occur | produced in the cable in Embodiment 1 of this invention The figure for demonstrating voltage detection when abnormality arises in the detection line in Embodiment 1 of this invention. The figure which shows schematic structure of the arc welding apparatus in Embodiment 2 of this invention. The figure for demonstrating the voltage detection at the time of normal in Embodiment 2 of this invention The figure for demonstrating the voltage detection at the time of abnormality in Embodiment 2 of this invention The figure for demonstrating the voltage detection at the time of abnormality in Embodiment 2 of this invention The figure for demonstrating the voltage detection at the time of abnormality in Embodiment 2 of this invention The figure for demonstrating the voltage detection at the time of abnormality in Embodiment 2 of this invention

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

(Embodiment 1)
FIG. 1 is a diagram illustrating a schematic configuration of an arc welding apparatus according to the first embodiment. In FIG. 1, an arc welding apparatus includes an arc welder 1, a first cable 5 as an output cable, a second cable 6 as an output cable, and a first voltage detection line for detecting an arc voltage. 1 detection line 7 and a second detection line 8 as a voltage detection line for detecting an arc voltage. The arc welder 1 supplies electric power between a welding electrode 13 and a base material 12 via a first cable 5 and a second cable 6 to generate an arc for arc welding. .

  The arc welder 1 is a main circuit part 2 for supplying power between the welding electrode 13 and the base material 12, and a first output terminal that is one of the two output terminals of the main circuit part 2. The voltage between the first output terminal 3 and the second output terminal 4, which are the output terminals 3, the second output terminal 4 that is the other output terminal, and the output terminals of the main circuit unit 2 is detected. Detection of the first voltage detection unit 9, a second voltage detection unit 10 for detecting an arc voltage using the first detection line 7 and the second detection line 8, and detection of the first voltage detection unit 9 A comparison unit 11 that compares the result with the detection result of the second voltage detection unit 10 is provided.

  The first cable 5 for supplying electric power to the welding electrode 13 side has one end side electrically connected to the first output terminal 3 and the other end side electrically connected to the welding electrode 13. ing. Further, the second cable 6 for supplying power to the base material 12 side is electrically connected to the second output terminal 4 at one end side and electrically connected to the base material 12 at the other end side. ing. Then, the main circuit current, that is, welding, is passed through the main circuit portion 2, the first output terminal 3, the first cable 5, the welding electrode 13, the base material 12, and the second cable 6. Current flows.

  The first detection line 7 provided for accurately detecting the arc voltage has one end electrically connected to the welding electrode 13 and the other end electrically connected to the second voltage detector 10. Has been. Further, the second detection line 8 provided for accurately detecting the arc voltage has one end electrically connected to the base material 12 and the other end electrically connected to the second voltage detection unit 10. It is connected. Then, the arc voltage is detected by the second voltage detection unit 10 via the first detection line 7 and the second detection line 8.

  Next, the operation of the arc welding apparatus will be described.

  When electric power is supplied between the welding electrode 13 and the base material 12 by the main circuit portion 2 of the arc welder 1, an arc is generated between the welding electrode 13 and the base material 12, and arc welding is performed. Is called. When arc welding is performed, the voltage between the output terminals of the main circuit unit 2 is detected by the first voltage detection unit 9. The arc voltage is detected by the second voltage detector 10. The detection result of the first voltage detection unit 9 and the detection result of the second voltage detection unit 10 are input to the comparison unit 11. In the comparison unit 11, the detection result of the first voltage detection unit 9 and the detection result of the second voltage detection unit 10 are compared. When the difference between the voltage detected by the first voltage detector 9 and the voltage detected by the second voltage detector 10 is greater than or equal to a predetermined value, the comparator 11 determines whether the first cable 5 or the second cable 6 or the first detection line 7 or the second detection line 8 is determined to be abnormal, and the main circuit unit 2 is controlled to stop the welding output. In addition, the determination result by the comparison part 11 is displayed, for example on the display part which is not shown in figure, and an operator can visually recognize it. The predetermined value used for the comparison is stored in the comparison unit 11. The predetermined value is, for example, a value of about 5V to 10V.

  Next, details of the determination by the comparison unit 11 will be described.

  The voltage detected by the first voltage detector 9 is higher than the voltage detected by the second voltage detector 10, and the voltage detected by the first voltage detector 9 and the second voltage detector 10 are When the difference from the detected voltage is a predetermined value or more, the comparison unit 11 determines that the first cable 5 or the second cable 6 is abnormal and stops the welding output by the main circuit unit 2. The reason for the determination will be described later.

  On the other hand, the voltage detected by the second voltage detector 10 is higher than the voltage detected by the first voltage detector 9, and the voltage detected by the first voltage detector 9 and the second voltage detector When the difference from the voltage detected at 10 is equal to or greater than a predetermined value, the comparison unit 11 determines that the first detection line 7 or the second detection line 8 is abnormal, and the welding output by the main circuit unit 2 Stop. The reason for the determination will be described later.

  Next, the reason why the above-described abnormality can be determined will be described with reference to FIGS. FIG. 2 shows the outside of the arc welder 1 in FIG. Accordingly, the reference numerals are the same as those in FIG. In FIG. 2, the detection point B is a voltage detection point of the first output terminal 3, and the detection point C is a voltage detection point of the second output terminal 4. The detection point A is a voltage detection point of the first detection line 7, and the detection point D is a voltage detection point of the second detection line 8. Further, the voltage between the arc voltage detection lines detected by the detection point A and the detection point D is shown as a detection line voltage VAD, and the voltage between the output terminals detected by the detection point B and the detection point C is indicated between the terminals. This is shown as voltage VBC.

  First, as shown in FIG. 2, when the output cable and the voltage detection line are not abnormal and normal, the relationship between the terminal voltage VBC and the detection line voltage VAD is as follows (formula 1): It becomes the relationship.

Terminal voltage VBC> Detection line voltage VAD (Equation 1)
This is because the inter-terminal voltage VBC is the detection line voltage VAD, which is an arc voltage, the voltage drop of the first cable 5 that is carrying the arc current by the main circuit unit 2, and the arc current by the main circuit unit 2. Is the sum of the voltage drop of the second cable 6 that is energized. Normally, the arc welding current is about 50 A to 500 A, and when the current in this region is energized to the first cable 5 or the second cable 6, the voltage is applied to the first cable 5 or the second cable 6. A descent occurs.

  Next, a case where an abnormality occurs in the output cable will be described with reference to FIG. 3 is different from FIG. 2 showing the normal state in that an abnormal portion 16 is generated. FIG. 3 shows an example in which the abnormal part 16 is generated in the second cable 6. If the abnormal portion 16 is in a half-broken state of the second cable 6, the resistance value at this portion increases, and the voltage drop at this portion increases remarkably. In this case, the relationship between the terminal voltage VBC and the detection line voltage VAD is expressed by the following (formula 2).

Terminal voltage VBC> Detection line voltage VAD (Formula 2)
If the difference between the terminal voltage VBC and the detection line voltage VAD is equal to or greater than a predetermined value, it can be determined that there is an abnormality, and the output from the main circuit unit 2 is stopped. The same applies to the case where the abnormal portion 16 that is in a partially disconnected state occurs in the first cable 5.

  Next, the case where the abnormal part 16 is in a disconnected state in FIG. 3 will be described. When the abnormal portion 16 of the second cable 6 is disconnected, the detection line voltage VAD is disconnected even if the inter-terminal voltage VBC is output, and the second cable 6 is disconnected and no arc is generated. The inter-voltage VAD is not detected and becomes “0 V”, and the relationship between the inter-terminal voltage VBC and the detection line voltage VAD is expressed by the following (formula 3).

Terminal voltage VBC >> Detection line voltage VAD = 0 (Formula 3)
Also in this case, if the difference between the terminal voltage VBC and the detection line voltage VAD is equal to or greater than a predetermined value, it can be determined that there is an abnormality, and the output is stopped. The same applies to the case where the abnormal portion 16 that is in a disconnected state occurs in the first cable 5.

  As described above, from (Equation 2) and (Equation 3), when the inter-terminal voltage VBC> the detection line voltage VAD and the difference between the inter-terminal voltage VBC and the detection line voltage VAD is a predetermined value or more, Can detect that an abnormality has occurred in the cable.

  Next, a case where an abnormality occurs in the voltage detection line of the arc voltage will be described with reference to FIG. 4 is different from FIG. 2 showing the normal state in that an abnormal portion 16 is generated. FIG. 4 shows an example in which an abnormal portion 16 is generated in the first detection line 7. If the abnormal portion 16 is in a half-broken state of the first detection line 7, the resistance value of this portion increases. Therefore, the relationship between the terminal voltage VBC and the detection line voltage VAD is expressed by the following (formula 4).

Terminal voltage VBC> Detection line voltage VAD (Formula 4)
Also in this case, if the difference between the terminal voltage VBC and the detection line voltage VAD is equal to or greater than a predetermined value, it can be determined that the first detection line 7 is abnormal, and the output is stopped. The same applies when the abnormal portion 16 is on the second detection line 8.

  Next, the case where the abnormal part 16 is in a disconnected state in FIG. 4 will be described. When the first detection line 7 is disconnected, even if an output is generated in the inter-terminal voltage VBC, the detection line voltage VAD cannot be detected because the first detection line 7 is disconnected. The relationship between the terminal voltage VBC and the detection line voltage VAD is expressed by the following (formula 5).

Terminal voltage VBC >> Detection line voltage VAD = 0 (Formula 5)
In this case as well, it is the same as in (Equation 3), and if the difference between the terminal voltage VBC and the detection line voltage VAD is equal to or greater than a predetermined value, it can be determined that there is an abnormality, and the output is stopped. The same applies when the abnormal portion 16 is on the second detection line 8.

  As described above, it is determined that an abnormality has occurred in the output cable or the voltage detection line by comparing the detection voltage detected by the first voltage detection unit 9 and the detection detection pressure detected by the second voltage detection unit 10. And the device can be stopped.

  In the above description, it can be determined that an abnormality has occurred in the output cable or the voltage detection line. However, even if there is no abnormality in the output cable and the voltage detection line itself, the connection between the output cable and the arc welding machine 1, the connection between the output cable and the extension cable, the connection part made a sliding type, the voltage Even when an abnormality occurs in the connection between the detection line and the arc welding machine 1, the same state as described above is obtained. Therefore, an abnormality in the output cable or the voltage detection line has occurred by performing the first embodiment, or an abnormality has occurred in the connection between the arc welding machine 1 and the output cable or the voltage detection line. Can be judged.

(Embodiment 2)
In the second embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. FIG. 5 is a diagram showing a schematic configuration of the arc welding apparatus according to the second embodiment. In FIG. 5, a different point from FIG. 1 demonstrated in Embodiment 1 is demonstrated. Also, description of the same points as in FIG. 1 will be omitted. In FIG. 5, the main points different from FIG. 1 are that a third voltage detector 14 that detects a voltage between the first detection line 7 and the second cable 6, the first cable 5, and the second cable 5. The fourth voltage detector 15 for detecting the voltage between the first and second detection lines 8 is provided. The third voltage detection unit 14 has a function of detecting a voltage VAC, which will be described later, and the fourth voltage detection unit 15 has a function of detecting the voltage VBD.

  In the first embodiment, it can be determined that an abnormality has occurred in the output cable or the voltage detection line. However, in the first embodiment, it is not possible to determine which route is abnormal. Therefore, as in the second embodiment, it is possible to determine which path is abnormal by detecting a plurality of voltages and comparing them. This determination method will be described with reference to FIGS.

  FIG. 6 shows the outside of the arc welder 1 in FIG. Accordingly, the reference numerals are the same as those in FIG. Further, the detection point A, the detection point B, the detection point C, and the detection point D are the same as those in FIG. The voltage between the detection point B and the detection point C is the voltage VBC, the voltage between the detection point A and the detection point C is the voltage VAC, and the voltage between the detection point B and the detection point D is the voltage. Let VBD be the voltage between the detection point A and the detection point D, and let it be the voltage VAD. Voltage VBC is the same as terminal voltage VBC in the first embodiment. Voltage VAD is the same as detection line voltage VAD in the first embodiment.

  Usually, when the voltage VBC when arc welding is performed and the voltage VAD in the vicinity of the arc are compared, there is a voltage drop corresponding to the impedance of the first cable 5 and the second cable 6, so the voltage VBC is better. It is higher than the voltage VAD. On the other hand, the first detection line 7 and the second detection line 8 are voltage detection lines, and almost no current flows. Therefore, the voltage drop due to the impedance is very small as compared with the case of the voltage VBC. Therefore, in the normal case, the following relationship (Equation 6) holds.

Voltage VBC> Voltage VAC≈Voltage VBD> Voltage VAD (Formula 6)
For example, the voltage drop in the case of the extension cable 20 m having an average current of 100 A and a cross-sectional area of 22 mm ² is about 1.7 V. And when an arc voltage is 20V, (Formula 6) becomes the following value concretely.

23.4V> 21.7V = 21.7V> 20V
Next, a case where an abnormality has occurred in the second cable 6 will be described with reference to FIG. 7 is different from FIG. 6 showing the normal state in that an abnormal portion 16 is generated. FIG. 7 shows an example in which the abnormal portion 16 is generated in the second cable 6. If the abnormal portion 16 is in a half-broken state of the second cable 6, the resistance value of this portion increases. In this case, in (Equation 6), it is considered that the resistance value of the portion including the detection point C increases, and the voltage having the detection point C as the detection end increases. Therefore, the following relationship (Equation 7) holds.

Voltage VBC> Voltage VAC> Voltage VBD> Voltage VAD (Formula 7)
For example, when the voltage of the abnormal part is 5 V, (Expression 7) is specifically the following value.

28.4V>26.7V>21.7V> 20V
Next, the case where the abnormal part 16 in FIG. 7 is in a disconnected state will be described. In this case, the following relationship (Formula 8) holds.

Voltage VBC = Voltage VAC >> Voltage VBD = Voltage VAD = 0 (Equation 8)
And when the relationship of (Formula 8) is materialized, it detects that the comparison part 11 is a disconnection of the 2nd cable 6, and stops the welding output by the main circuit part 2. FIG.

  Next, a case where an abnormality has occurred in the second detection line 8 will be described with reference to FIG. 8 is different from FIG. 6 showing the normal state in that an abnormal portion 16 is generated. FIG. 8 shows an example in which the abnormal portion 16 is generated in the second detection line 8. If the abnormal portion 16 is in a half-broken state of the second detection line 8, the resistance value of this portion increases. In this case, the following relationship (Equation 9) holds.

Voltage VBC> Voltage VAC> Voltage VBD> Voltage VAD (Equation 9)
For example, when the voltage of the abnormal part is 5 V, (Expression 9) is specifically the following value.

23.4V>21.7V>16.7V> 15V
Here, regarding (Expression 7) and (Expression 9), which are expressions of the semi-breaking state, values are different between (Expression 7) and (Expression 9) when a numerical value is entered in a specific example. However, the magnitude relationship between the voltages is the same. Therefore, an abnormal location cannot be specified only by the magnitude relationship of each voltage. Therefore, a method for determining by a control method (constant voltage control welding or constant current control welding) will be described.

  The control method is the detection voltage of the second voltage detection unit 10 with respect to the second cable 6 being in a partially disconnected state (Equation 7) and the second detection line 8 being in a partially disconnected state (Equation 9). In the case of constant voltage control welding using the voltage VAD (hereinafter referred to as CV welding), the distance between the welding electrode 13 and the base material 12 with respect to the command arc voltage (setting voltage set using a setting unit not shown). Is a certain standard distance (for example, 10 to 20 mm), the standard current value in the normal state is determined. That is, if constant voltage control is performed and the distance between the welding electrode 13 and the base material 12 is constant and a standard distance, the constant voltage and the first output terminal 3 to the second output terminal 4 in the constant voltage control are used. The standard current value is determined from the circuit resistance value. The standard current value is stored in the comparison unit 11.

  When the second cable 6 is in a half-broken state, constant voltage control is performed with the voltage VAD, and the resistance value of the main circuit unit 2 (from the first output terminal 3 to the second voltage is maintained with the voltage being constant). Even if the circuit resistance value up to the output terminal 4 increases, the voltage VBC increases, but if the distance between the welding electrode 13 and the base material 12 does not change, the welding current does not change from the standard current value. . On the other hand, when the second detection line 8 is in a half-broken state, the resistance value of the second detection line 8 increases and the feedback voltage (voltage VAD) is compared with the normal state. Therefore, the control voltage (voltage VBC output from the main circuit unit 2) is higher than the command value (set voltage), and as a result, the welding current is higher than the standard current value. The comparison of the feedback voltage is performed in the comparison unit 11.

  Thus, in the state of (Equation 7) and (Equation 9), the magnitude relationship of each voltage becomes the same, but in the case of CV welding, the second detection is performed when the welding current value becomes higher than the standard current value. It can be determined that the line 8 is abnormal. If the welding current value is the same as the standard current value, it can be determined that the second cable 6 is abnormal.

  Further, even in the case of constant current control welding (hereinafter referred to as CC welding), a standard voltage value that is a standard welding voltage in a normal state according to a command current (a setting current set by a setting unit (not shown)) is determined. The abnormal part can be determined. The standard voltage value is determined if constant current control is performed and the distance between the welding electrode 13 and the base material 12 is constant and a standard distance. That is, the standard voltage value is determined from the constant current and the circuit resistance value from the first output terminal 3 to the second output terminal 4. The standard voltage value is stored in the comparison unit 11.

  When the second cable 6 is in a partially disconnected state, the resistance value of the main circuit unit 2 (circuit resistance value from the first output terminal 3 to the second output terminal 4) increases in the constant current control state. The voltage (voltage VBC) detected between the output terminals is higher than the sum of the standard voltage value at normal time and the voltage drop of the cable, and the detected voltage (voltage VAD) is equal to the standard voltage value. It can be determined that the second cable 6 is abnormal. On the contrary, in the case where the second detection line 8 is in a half-broken state, the detection voltage (voltage VAD) is lower than the standard voltage value (normal state voltage VAD). It can be determined that the detection line 8 is abnormal.

  Next, the case where the abnormal part 16 in FIG. 8 is in a disconnected state will be described. In this case, the following relationship (Formula 10) holds.

Voltage VBC> Voltage VAC >> Voltage VBD = Voltage VAD = 0 (Equation 10)
And when the relationship of (Formula 10) is materialized, it detects that the comparison part 11 is the disconnection of the 2nd detection line 8, and stops the welding output by the main circuit part 2. FIG.

Here, when (Equation 10) and (Equation 8) are compared, it looks the same. However, (Expression 8) is an expression when the second cable 6 is in a disconnected state and no current flows through the cable, and the voltage VBC and the voltage VAC are the same. On the other hand, (Expression 10) is an expression in the case where the second detection line 8 is in a disconnected state, and since a current flows through the cable, the voltage drop of the first cable 5 appears as a difference. For example, the difference between the case of (Equation 10) and the case of (Equation 8) can be determined because a difference of an average current of 100 A, an extension cable of 20 mm with a cross-sectional area of 22 mm ² and a voltage drop of about 1.7 V occurs. That is, from the relationship between the voltage VBC and the voltage VAC, the comparison unit 11 can determine whether the second cable 6 is disconnected or the second detection line 8 is disconnected.

  When the voltage drop of the cable is a slight difference, the difference between the voltage VBC and the voltage VAC is also a slight difference, and it may be difficult to judge. In such a case, it is possible to determine the disconnection portion more clearly by detecting the welding current with a welding current detection unit (not shown) provided in the main circuit unit 2. That is, when the welding current of the main circuit portion 2 is “0 A”, it can be determined that an abnormality has occurred in the second cable 6. On the other hand, when the current of the main circuit unit 2 is not “0 A”, it can be determined that an abnormality has occurred in the second detection line 8. The welding current detected by the welding current detection unit of the main circuit unit 2 is input to the comparison unit 11 and used for determination.

  Next, a case where an abnormality has occurred in the first cable 5 will be described with reference to FIG. 9 is different from FIG. 6 showing the normal state in that an abnormal portion 16 is generated. FIG. 9 shows an example in which an abnormal portion 16 is generated in the first cable 5. If the abnormal portion 16 is in a half-broken state of the first cable 5, the resistance value of this portion increases. In this case, it is considered that the voltage having the detection point B as the detection end increases. Therefore, the following relationship (Equation 11) holds.

Voltage VBC> Voltage VBD> Voltage VAC> Voltage VAD (Equation 11)
For example, when the voltage of the abnormal part is 5 V, (Expression 11) is specifically the following value.

28.4V> 26.7V >>21.7V> 20V
And when the relationship of (Formula 11) is materialized, the comparison part 11 detects that it is abnormal of the 1st cable 5, and stops the welding output by the main circuit part 2. FIG.

  Next, the case where the abnormal part 16 in FIG. 9 is in a disconnected state will be described. In this case, the following relationship (Formula 12) holds.

Voltage VBC = Voltage VBD >> Voltage VAC = Voltage VAD = 0 (Equation 12)
And when the relationship of (Formula 12) is materialized, the comparison part 11 detects that it is a disconnection of the 1st cable 5, and the main circuit part 2 stops a welding output.

  Next, a case where an abnormality has occurred in the first detection line 7 will be described with reference to FIG. 10 is different from FIG. 6 showing the normal state in that an abnormal portion 16 is generated. FIG. 10 shows an example in which the abnormal portion 16 is generated in the first detection line 7. If the abnormal portion 16 is in a half-broken state of the first detection line 7, the resistance value of this portion increases. In this case, the following relationship (Formula 13) holds.

Voltage VBC> Voltage VBD> Voltage VAC> Voltage VAD (Formula 13)
For example, when the voltage of the abnormal part is 5 V, (Expression 13) is specifically the following value.

23.4V>21.7V>16.7V> 15V
Here again, the values are different between (Equation 11) and (Equation 13) if numerical values are entered in a specific example. However, the magnitude relationship of each voltage is the same. Therefore, here, a method of determining an abnormal location by a control method (constant voltage control welding or constant current control welding) will be described.

  With respect to (Equation 11) when the first cable 5 is in a partially disconnected state and (Equation 13) when the first detection line 7 is in a partially disconnected state, the control method is In the case of constant voltage control welding (hereinafter referred to as CV welding) using the voltage VAD which is the detection voltage, the welding electrode 13 and the mother are set against the command arc voltage (setting voltage set using a setting unit not shown). If the distance from the material 12 is a constant standard distance (for example, 10 to 20 mm), the standard current value in a normal state is determined. That is, if constant voltage control is performed and the distance between the welding electrode 13 and the base material 12 is constant and a standard distance, the constant voltage and the first output terminal 3 to the second output terminal 4 in the constant voltage control are used. The standard current value is determined from the circuit resistance value. The standard current value is stored in the comparison unit 11.

  When the first cable 5 is in a half-broken state, constant voltage control is performed with the voltage VAD, and the resistance value of the main circuit unit 2 (from the first output terminal 3 to the second voltage is maintained with the voltage being constant). Even if the circuit resistance value to the output terminal 4 increases, the voltage VBC increases, but if the distance between the welding electrode 13 and the base material 12 does not change, the welding current does not change from the standard current value. The comparison of the welding current is performed in the comparison unit 11. The welding current is detected by a welding current detection unit (not shown) provided in the main circuit unit 2.

  On the contrary, when the first detection line 7 is in a semi-breaking state, the feedback voltage (voltage VAD) is lower than the voltage VAD in the normal state. Therefore, the control voltage (voltage VBC output from the main circuit unit 2) is higher than the command value (set voltage), and as a result, the welding current is higher than the standard current value. The comparison of the feedback voltage (voltage VAD) is performed in the comparison unit 11.

  In this way, in (Equation 11) and (Equation 13), the relationship between the voltage differences is the same, but in CV welding, the first cable 5 is abnormal when the standard current value and the welding current value are the same. It can be judged that. Conversely, if the welding current is higher than the standard current value, it can be determined that the first detection line 7 is abnormal.

  Further, even in the case of constant current control welding (hereinafter referred to as CC welding), a standard voltage value that is a standard welding voltage in a normal state according to a command current (a setting current set by a setting unit (not shown)) is determined. The abnormal part can be determined. The standard voltage value is determined if constant current control is performed and the distance between the welding electrode 13 and the base material 12 is constant and a standard distance. That is, the standard voltage value is determined from the constant current and the circuit resistance value from the first output terminal 3 to the second output terminal 4. The standard voltage value is stored in the comparison unit 11.

  When the first cable 5 is in a partially disconnected state, the resistance value of the main circuit unit 2 (circuit resistance value from the first output terminal 3 to the second output terminal 4) increases in the constant current control state. Therefore, the detected voltage (voltage VBC) is higher than the total value of the standard voltage value and the voltage drop at normal time, the detected voltage (voltage VAD) and the standard voltage value are the same, and the first cable 5 is It can be determined that it is abnormal. On the other hand, when the first detection line 7 is in a half-broken state, the detected welding voltage (voltage VAD) is lower than the standard voltage value. Therefore, it can be determined that the first detection line 7 is abnormal.

  Next, the case where the abnormal part 16 in FIG. 10 is in a disconnected state will be described. In this case, the following relationship (Formula 14) is established.

Voltage VBC> Voltage VBD >> Voltage VAC = Voltage VAD = 0 (Formula 14)
And when the relationship of (Formula 14) is materialized, the comparison part 11 detects that it is a disconnection of the 1st detection line 7, and stops the welding output by the main circuit part 2. FIG.

Here, when (Equation 12) and (Equation 14) are compared, it looks the same. However, (Equation 12) is an equation when the first cable 5 is disconnected, and no current flows through the cable, so the voltage VBC and the voltage VBD are the same. On the other hand, (Expression 14) is an expression when the first detection line 7 is disconnected, and a current flows through the cable, and the voltage drop of the first cable 5 appears as a difference. For example, the difference between (Equation 12) and (Equation 14) is the difference between the voltage VBC and the voltage VBD because a difference of an average current of 100 A, an extension cable of 20 mm with a cross-sectional area of 22 mm ² , and a voltage drop of about 1.7 V occurs. It can be judged from the relationship of the size. That is, it can be determined from the relationship between the voltage VBC and the voltage VBD whether the first cable 5 is disconnected or the first detection line 7 is disconnected.

  When the voltage drop of the cable is a slight difference, the difference between the voltage VBC and the voltage VBD is also a slight difference, and it may be difficult to make a determination. In such a case, by detecting the welding current of the main circuit portion 2, it is possible to determine the disconnection portion more clearly. That is, when the welding current of the main circuit portion 2 is “0 A”, it can be determined that an abnormality has occurred in the first cable 5. On the other hand, when the current of the main circuit unit 2 is not “0 A”, it can be determined that an abnormality has occurred in the first detection line 7.

  As described above, by comparing each voltage detection value, it is possible to detect an abnormality and a path where the abnormality has occurred, and to stop the welding output based on the abnormality detection. Then, by further comparing the welding currents, it is possible to determine the disconnection part more clearly.

  Also in the second embodiment, the determination result of the comparison unit 11 may be displayed on a display unit (not shown) so that the operator can visually recognize it.

  In CV welding, there are a welding method in which arcs and short circuits are periodically repeated, and a method using a pulse current (voltage), and it may be difficult to compare with an instantaneous voltage or an instantaneous current. Therefore, the time axis may be widened and the comparison with the average value may be performed. In addition, since there is an AC value as well as a DC value, an effective value may be used as the comparison value.

(Embodiment 3)
The point of using the current detection function of the main circuit unit 2 will be described again in order to make the determination more clearly in the disconnection determination in the second embodiment. (Equation 8) and (Equation 10) shown in the second embodiment are shown side by side below. Note that (Expression 8) represents an expression when the second cable 6 is disconnected, and (Expression 10) represents an expression when the second detection line 8 is disconnected.

Voltage VBC = Voltage VAC >> Voltage VBD = Voltage VAD = 0 (Equation 8)
Voltage VBC> Voltage VAC >> Voltage VBD = Voltage VAD = 0 (Equation 10)
The difference between the voltage VBC and the voltage VAC in (Equation 10) is only the voltage drop. Therefore, it may be difficult to distinguish when the current value is low. Therefore, the current detection function of the main circuit unit 2 is added to the determination. Specifically, in the case of (Equation 8), since the second cable 6 is disconnected, the welding current of the main circuit portion 2 is “0A”, while in the case of (Equation 10), the second Since the detection line 8 is disconnected, the welding current of the main circuit portion 2 is not “0A”. Therefore, the abnormal location becomes clear by using the welding current of the main circuit portion 2 for the determination.

  Similarly, even in the cases of (Equation 12) and (Equation 14), by using the welding current of the main circuit portion 2 for the determination, the abnormal portion becomes clear.

  The arc welding apparatus of the present invention can detect abnormalities such as disconnection and half disconnection of the output cable during use and abnormality of the connection part of the cable, etc., and can assist in the early recovery of the path constituting the arc welding apparatus, or arc welding. Since the apparatus can be protected, the reliability can be improved, and the present invention is industrially useful as an arc welding apparatus having a voltage detection line for detecting an arc voltage.

DESCRIPTION OF SYMBOLS 1 Arc welder 2 Main circuit part 3 1st output terminal 4 2nd output terminal 5 1st cable 6 2nd cable 7 1st detection line 8 2nd detection line 9 1st voltage detection part 10 2nd voltage detection part 11 Comparison part 12 Base material 13 Electrode for welding 14 3rd voltage detection part 15 4th voltage detection part 16 Abnormal part

Claims (9)

An arc welding apparatus for performing arc welding by supplying electric power between a welding electrode and a base material,
A main circuit section for supplying electric power between the welding electrode and the base material;
A first cable that is electrically connected to a first output terminal that is one of the two output terminals of the main circuit portion and supplies power to the welding electrode;
A second cable that is electrically connected to a second output terminal that is the other output terminal of the main circuit portion and supplies power to the base material side;
A first detection line connected to the side of the welding electrode to detect an arc voltage in the arc;
A second detection line connected to the base material side for detecting an arc voltage in the arc;
A first voltage detection unit for detecting a voltage between output terminals of the main circuit unit;
A second voltage detection unit for detecting an arc voltage electrically connected to the first detection line and the second detection line;
A comparator that compares the voltage detected by the first voltage detector with the voltage detected by the second voltage detector;
When the difference between the voltage detected by the first voltage detection unit and the voltage detected by the second voltage detection unit is greater than or equal to a predetermined value, the comparison unit may detect the first cable or the second cable. An arc welding apparatus that determines that a cable or the first detection line or the second detection line is abnormal. A third voltage detector for detecting a voltage between the first detection line and the second cable;
A fourth voltage detection unit for detecting a voltage between the first cable and the second detection line,
The comparison unit includes a voltage detected by the first voltage detection unit, a voltage detected by the second voltage detection unit, a voltage detected by the third voltage detection unit, and a voltage detected by the fourth voltage detection unit. The arc welding apparatus according to claim 1, wherein the arc welding apparatus determines that the first cable, the second cable, the first detection line, or the second detection line is abnormal based on the first cable. Arc welding equipment performs constant current control welding,
In the comparison unit, the detection voltage of the third voltage detection unit is higher than the detection voltage of the second voltage detection unit, and the detection voltage of the fourth voltage detection unit is higher than the detection voltage of the third voltage detection unit. When the detection voltage of the first voltage detection unit is higher than the detection voltage of the fourth voltage detection unit and the detection result of the second voltage detection unit is the same as the standard voltage value at normal time , Determine that the first cable is abnormal,
The detection voltage of the fourth voltage detection unit is higher than the detection voltage of the second voltage detection unit, the detection voltage of the third voltage detection unit is higher than the detection voltage of the fourth voltage detection unit, When the detection voltage of the first voltage detection unit is higher than the detection voltage of the third voltage detection unit and the detection result of the second voltage detection unit is the same as the standard voltage value, the second Judge that the cable is abnormal,
The detection voltage of the third voltage detection unit is higher than the detection voltage of the second voltage detection unit, the detection voltage of the fourth voltage detection unit is higher than the detection voltage of the third voltage detection unit, When the detection voltage of the second voltage detection unit is higher than the detection voltage of the fourth voltage detection unit and the detection result of the second voltage detection unit is lower than the standard voltage value, the first detection line is Judge that it is abnormal,
The detection voltage of the fourth voltage detection unit is higher than the detection voltage of the second voltage detection unit, the detection voltage of the third voltage detection unit is higher than the detection voltage of the fourth voltage detection unit, When the detection voltage of the first voltage detection unit is higher than the detection voltage of the third voltage detection unit and the detection result of the second voltage detection unit is lower than the standard voltage value, The arc welding apparatus according to claim 2, wherein the detection line is determined to be abnormal. In the comparison unit, the detection voltage of the third voltage detection unit and the detection voltage of the second voltage detection unit are zero, and the detection voltage of the fourth voltage detection unit is higher than the detection voltage of the third voltage detection unit. If the detection voltage of the first voltage detection unit is the same value as the detection voltage of the fourth voltage detection unit, it is determined that the first cable is disconnected,
The detection voltage of the fourth voltage detection unit and the detection voltage of the second voltage detection unit are zero, and the detection voltage of the third voltage detection unit is higher than the detection voltage of the fourth voltage detection unit. When the detection voltage of the first voltage detection unit is the same value as the detection voltage of the third voltage detection unit, it is determined that the second cable is disconnected,
The detection voltage of the third voltage detection unit and the detection voltage of the second voltage detection unit are zero, the detection voltage of the fourth voltage detection unit is higher than the detection voltage of the third voltage detection unit, When the detection voltage of the first voltage detection unit is higher than the detection voltage of the fourth voltage detection unit, it is determined that the first detection line is disconnected,
The detection voltage of the fourth voltage detection unit and the detection voltage of the second voltage detection unit are zero, and the detection voltage of the third voltage detection unit is higher than the detection voltage of the fourth voltage detection unit. The arc welding apparatus according to claim 2, wherein when the detection voltage of the first voltage detection unit is higher than the detection voltage of the third voltage detection unit, it is determined that the second detection line is disconnected. It has a welding current detector that detects the welding current,
The comparison unit detects the voltage detected by the first voltage detection unit, the voltage detected by the second voltage detection unit, the voltage detected by the third voltage detection unit, and the detection by the fourth voltage detection unit. The first cable, the second cable, the first detection line, or the second detection line is determined to be abnormal based on the measured voltage and the welding current detected by the welding current detection unit. Arc welding equipment. Arc welding equipment performs constant voltage control welding,
In the comparison unit, the detection voltage of the third voltage detection unit is higher than the detection voltage of the second voltage detection unit, and the detection voltage of the fourth voltage detection unit is higher than the detection voltage of the third voltage detection unit. When the detection voltage of the first voltage detection unit is higher than the detection voltage of the fourth voltage detection unit and the welding current value detected by the welding current detection unit is the same as the welding current value in the normal state , Determine that the first cable is abnormal,
The detection voltage of the fourth voltage detection unit is higher than the detection voltage of the second voltage detection unit, the detection voltage of the third voltage detection unit is higher than the detection voltage of the fourth voltage detection unit, When the detection voltage of the first voltage detection unit is higher than the detection voltage of the third voltage detection unit, and the welding current value detected by the welding current detection unit is the same as the welding current value in a normal state Determines that the second cable is abnormal,
The detection voltage of the third voltage detection unit is higher than the detection voltage of the second voltage detection unit, the detection voltage of the fourth voltage detection unit is higher than the detection voltage of the third voltage detection unit, When the detection voltage of the voltage detection unit is higher than the detection voltage of the fourth voltage detection unit and the welding current value detected by the welding current detection unit is higher than the welding current value in the normal state, the first Is determined to be abnormal,
The detection voltage of the fourth voltage detection unit is higher than the detection voltage of the second voltage detection unit, the detection voltage of the third voltage detection unit is higher than the detection voltage of the fourth voltage detection unit, When the detection voltage of the first voltage detection unit is higher than the detection voltage of the third voltage detection unit, and the welding current value detected by the welding current detection unit is higher than the welding current value in a normal state The arc welding apparatus according to claim 5, wherein the second detection line is determined to be abnormal. In the comparison unit, the detection voltage of the third voltage detection unit and the detection voltage of the second voltage detection unit are zero, and the detection voltage of the fourth voltage detection unit is higher than the detection voltage of the third voltage detection unit. If the detection voltage of the first voltage detection unit is the same as the detection voltage of the fourth voltage detection unit and the welding current value detected by the welding current detection unit is zero, the first cable is disconnected. It is determined that
The detection voltage of the fourth voltage detection unit and the detection voltage of the second voltage detection unit are zero, and the detection voltage of the third voltage detection unit is higher than the detection voltage of the fourth voltage detection unit. When the detection voltage of the first voltage detection unit is the same as the detection voltage of the fourth voltage detection unit and the welding current value detected by the welding current detection unit is zero, the second cable is Judge that it is a disconnection,
The detection voltage of the third voltage detection unit and the detection voltage of the second voltage detection unit are zero, the detection voltage of the fourth voltage detection unit is higher than the detection voltage of the third voltage detection unit, When the detection voltage of the first voltage detection unit is higher than the detection voltage of the fourth voltage detection unit and the welding current value detected by the welding current detection unit is not zero, the first detection line is broken. Judge that there is
The detection voltage of the fourth voltage detection unit and the detection voltage of the second voltage detection unit are zero, and the detection voltage of the third voltage detection unit is higher than the detection voltage of the fourth voltage detection unit. When the detection voltage of the first voltage detection unit is higher than the detection voltage of the third voltage detection unit and the welding current value detected by the welding current detection unit is not zero, the second detection line is The arc welding apparatus according to claim 5, wherein the arc welding apparatus is determined to be a disconnection. The arc welding apparatus according to claim 1, wherein the detected voltage is used as an average value for comparison. The arc welding apparatus according to claim 1, wherein the detected voltage is used as an effective value for comparison.

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