JP4534770B2 - Welding monitoring device and welding monitoring method - Google Patents

Description

  The present invention relates to a technique for monitoring the quality of welding. The present invention can be used to monitor the quality of a welding process that is currently being performed, but can also be used to monitor the quality of a welding process that has been performed in the past by analyzing data collected in the past. .

A technique is known in which various welding indices are measured over time during the welding process to monitor the quality of the welding process.
For example, in Patent Document 1, when the welding process is being performed, the welding current, the welding voltage, the welding speed, the wire feeding speed, and the like are continuously measured, and the measured value of the welding index exceeds a predetermined range. A welding monitoring device for lighting a warning lamp is described.
JP-A-9-57442

In the technique of Patent Document 1, if the normal range of the welding index is set to be narrow, it becomes easy to be affected by noise and the like, and erroneous determination frequently occurs. On the other hand, if the normal range of the welding index is set wide, the sensitivity of abnormality determination becomes dull. With the technique of Patent Document 1, it is easy to erroneously determine that a normal one is abnormal or to erroneously determine that an abnormal one is normal.
In order to reduce erroneous determination, a technique has been proposed in which the number of times the measured value of the welding index exceeds the normal range is counted and the count number is compared with the allowable count number range. According to this technology, it is possible to prevent an erroneous determination that is abnormal due to a single occurrence that occurs even during normal operation, and to reduce the probability of erroneous determination.
However, even with the technique of comparing the count number with the allowable count number range, it is difficult to appropriately set the allowable count number range, and the probability of erroneous determination cannot be reduced sufficiently.
The conventional technology cannot accurately monitor the quality of welding. The present invention solves that problem. The present invention provides a technique capable of sufficiently reducing the probability of erroneous determination in accurately monitoring the quality of welding. And it becomes possible to discover abnormality of welding conditions or a welding apparatus at an early stage.

The present invention can be embodied in an apparatus that monitors the quality of welding that is repeatedly performed while switching welding conditions . This monitoring device has a measuring means for measuring a welding index over time in a measurement period during welding in each welding, and the measured welding index is within a predetermined index range determined for welding conditions at that time. It comprises a counting means for counting a period, the calculation means to calculate the period ratio of the time period for the measurement period.
The welding index here refers to an index that can be measured during the execution of the welding process and affects the welding quality. For example, welding current, welding voltage, welding speed, wire feed speed, wire feed force, shield gas pressure, shield gas flow rate and the like can be mentioned. The measurement period can be selected, and the length is adjusted according to the measurement environment.
This apparatus can monitor the quality of welding in almost real time by using the welding index measured immediately before and the welding index measured at the present time as analysis targets. By using a welding index measured and stored in the past as an analysis target, it is possible to determine whether the welding performed in the past is good or bad.

FIG. 3 shows an example of measurement results obtained by measuring the welding current C (which is an example of a welding index) over time during welding (welding period). It is known that the welding current in the case of normal welding is in the normal range CL to CU.
If the welding index is continuously measured over time, the welding index often deviates from the normal range CL to CU. Even in the case of normal welding, the welding index often deviates from the normal range CL to CU, so it is extremely difficult to determine the quality of the welding.
In FIG. 3, periods indicated by symbols G and H indicate periods during which the welding index deviates from the normal range CL to CU. At this time, there is a slight departure in period G and a large departure in period H. If the number of deviations is counted, the deviations occur once in each of the period G and the period H.
Through our research, it has been found that the factor that greatly affects the welding quality is not the deviating scale, the number of deviating times, and the deviating time.
For example, in the case shown in FIG. 3, there is a slight deviation in the period G and a great deviation in the period H. Considering on a deviating scale, the weld quality of period H should be more serious than period G. However, in practice, the welding quality in the period G is more serious than the period H. In the period H, the welding index greatly deviates from the normal range, but since it returns to the normal range in a short time, the influence on the welding quality is small as a result. On the other hand, in period G, the welding index deviates slightly from the normal range, but the welding index deviates from the normal range over a long period of time, resulting in an effect on the welding quality. Is big.
In the conventional technique, when the welding index deviates from the normal range, it is determined as abnormal, and thus erroneous determination frequently occurs. In order to avoid this, erroneous determination cannot be prevented even if the normal range is set wide. In the case of FIG. 3, the period G in which the deterioration of the welding quality is serious is overlooked, and the period H in which the deterioration of the welding quality is not so much is made abnormal.
Even if the number of times of deviating from the normal range is counted, determination cannot be made so that the period G in which the deterioration of the welding quality is serious is regarded as important and the period H in which the deterioration of the welding quality is not so much is neglected. In the technique for counting the number of times, the period G and the period H are not distinguished in each case, and each counts as one.

The monitoring device of the present invention measures the period during which the measured welding index is in the predetermined index range. In the case of FIG. 3, the elapsed time other than the period G and the period H is measured. The time measured is compared with the measurement period Tm. That is, the period ratio between the timing periods with respect to the measurement period is calculated. In the case of FIG.
(Measurement period Tm−duration Tf of period G−duration Tf of period H) / (measurement period Tm) is calculated.
If the measured welding index stays within the predetermined index range over the entire measurement period, the period rate is 1.00. When there is a period that deviates from the predetermined index range for a short period like the period H, the period rate slightly decreases from 1.00, but still remains close to 1.00. When there is a period that deviates from the predetermined index range over a long period of time, such as the period G, the period rate is significantly lower than 1.00.
According to this welding monitoring apparatus, since the focus is on the period rate, the degree of influence on the welding quality can be grasped quantitatively, and the quality of welding can be accurately monitored.
Note that the predetermined index range may be other than the normal range. In this case, the period rate is
It is calculated by (duration Tf of period G + duration Tf of period H) / (measurement period Tm). Whichever is the period rate, the degree of influence on the welding quality can be quantified and understood.

Monitoring equipment of the present invention, the period ratio calculating means is calculated, that further comprise a storage memory means for information and pair to storage memory for identifying the welding condition at that time.
The period rate calculated by the calculation means is an index that quantitatively indicates the welding quality. By accumulating and storing the calculated period rate, it becomes possible to analyze welding performed in the past. Further, it can be used to update a predetermined period rate range to be compared with the calculated period rate from the transition of the past period rate.

The monitoring apparatus of the present invention further includes a determination unit and a display unit. The determination means performs a first determination for determining whether or not the period rate calculated by the calculation means is within a predetermined abnormal range. The determination means, when the period rate in the first judgment is determined to be in the abnormal range, a second determination time constant stored in the storage memory means to determine the constant whether the abnormal range Is further implemented . In this case, among the period rates stored in the storage unit, the period rate at the time of the last welding performed under the same welding conditions is set as the determination target. Based on the determination result of the determination means, the display means displays information that can specify the welding condition when it is determined that the period rate has continuously become an abnormal range in a plurality of times of welding under the same welding condition. To do.
If said determination is carried out, it can be determined whether the determination result of abnormality is limited only at the time of welding, or whether it is continuous from the time of welding under the same welding conditions . When the continuously in the welding of the same welding conditions are determined to be abnormal it may be estimated that there is a problem with the welding condition, by displaying the information that can specify the welding condition, welding condition Can be reviewed .

Determining means, when it is determined that the period index in the first determination is in the abnormal range, the period ratio at last carried out the welding, which is stored in the storage memory unit regardless of welding conditions, the abnormal range It is preferable to further determine whether or not there is. In this case, the display means is an apparatus that performs welding when it is determined that the period rate is continuously within the abnormal range in a plurality of times of welding regardless of welding conditions based on the determination result of the determination means. Furthermore, the display child is preferred the information prompting the inspection of.
When the above determination is made, it can be determined whether the determination result is limited to the time of the welding or is continuous from the previous welding . If it is continuously determined to be abnormal regardless of the welding conditions, it can be estimated that there is a problem with the apparatus that has performed welding, and a display that prompts inspection of the apparatus that has performed welding is appropriately performed. Can

The technique of the present invention is also embodied in a method for monitoring the quality of welding repeatedly performed while switching welding conditions . This monitoring method includes a step of measuring a welding index over time in a measurement period during welding in each welding, and a period in which the measured welding index is within a predetermined index range determined for welding conditions at that time. A step of calculating a period rate between timings for a measurement period, a step of accumulating and storing the calculated period rate in combination with information capable of specifying welding conditions at that time, and a calculated period rate and it executes a first determination determines whether located in a predetermined abnormal range, when it is determined to be in the abnormal range in the first determination was last performed at the same welding conditions stored period rate during welding, a determination step of further performing a second determination of determining whether the abnormal range, based on the determination result of the determination step, the period in a plurality of times of welding by the same welding conditions When but was found to have an abnormal range continuously, comprising a display step of displaying the information that can specify the welding conditions.
According to this monitoring method, the degree of welding quality can be quantified and understood, and the quality of welding can be accurately monitored. Also, it becomes possible to detect abnormalities in welding conditions at an early stage.
In addition, in the determination step, when it is determined in the first determination that the period rate is in the abnormal range, the stored period rate at the time of the last performed welding is in the abnormal range regardless of the welding conditions. It is preferable to further determine whether or not there is. In this case, the display means is a device that performs welding when it is determined that the period rate is continuously within the abnormal range in a plurality of times of welding regardless of welding conditions based on the determination result of the determination step. It is preferable to further display information for prompting the inspection.

  According to the present invention, it is possible to accurately monitor the quality of welding, prevent the occurrence of welding defects, and detect abnormalities in welding equipment and welding conditions at an early stage.

First, main forms of the embodiments described below are listed.
(Mode 1) A welding facility includes a welding device that performs welding and a monitoring device that monitors the welding performed by the welding device.
(Mode 2) The monitoring device is configured by a welding index measuring device provided in the welding device, a monitoring processing device that performs processing based on the measurement result of the measuring device, and the like.
(Mode 3) The monitoring device includes a measuring instrument that measures a welding current, a welding voltage, a wire feeding force, and the like, which are welding indices.
(Mode 4) The monitoring processing device includes a computer device including a processing device and a storage device.

Example 1
Embodiments of the present invention will be described with reference to the drawings. FIG. 1 schematically shows the welding equipment of this embodiment. The welding equipment shown in FIG. 1 is a part of equipment for manufacturing an automobile body, and is an equipment for welding a plurality of metal parts to form an automobile body.
The welding equipment shown in FIG. 1 sequentially welds a plurality of workpieces A, B, C,. Each workpiece A, B, C is composed of a plurality of metal parts 101, 102, 103, 104. As shown in FIG. 1, a welding line (welding point) L <b> 1 for welding both parts 101 and 102 is defined. Similarly, a welding line L2 is defined between the parts 102 and 103, a welding line L3 is defined between the parts 103 and 104, and a welding line is defined between the parts 104 and 101. L4 is defined. The welding equipment sequentially performs welding at the positions of the welding lines L1 to L4. That is, the welding equipment sequentially welds the workpiece A to the positions of the welding lines L1 to L4, then sequentially welds the workpiece B to the positions of the welding lines L1 to L4, and then to the workpiece C. Then, welding is sequentially performed at the positions of the welding lines L1 to L4.

As shown in FIG. 1, the welding equipment mainly includes a welding device 10, a monitoring processing device 50 that executes processing for monitoring welding performed by the welding device 10, and processing results of the monitoring processing device 50. It consists of a monitor 80 or the like for display.
First, the welding apparatus 10 will be described. The welding apparatus 10 is an apparatus that performs (constructs) consumable electrode type gas shielded arc welding. As shown in FIG. 1, the welding apparatus 10 includes a welding torch 36 to which a power supply tip 38 is attached, an industrial robot 24 that adjusts the position of the welding torch 36, and a welding wire 20 that is fed to the welding torch 36. A wire feeding device 32 for welding, a welding power source 16 for supplying welding power, a control device 14 for controlling the operation of the robot 24, the wire feeding device 32 and the welding power source 16, and the like.
The welding power source 16 includes a current measuring device 42 that measures a welding current over time and a voltage measuring device 44 that measures a welding voltage over time.
The wire feeding device 32 includes a measuring instrument (not shown) that measures the force (wire feeding force) required to feed the welding wire 20 over time. The wire feeding force can be measured, for example, by detecting the driving current of the wire feeding device 32. The wire feeding force increases due to the progress of wear (inner surface roughness) of the conduit cable 34, the power feed tip 38, and the like, for example.

  The welding wire 20 and shield gas are supplied to the welding torch 36. The welding wire 20 is unwound from the wire creel 18 by the wire supply device 32 and guided to the conduit cable 34. The shielding gas is supplied from the gas cylinder 22 to the hose 26 while being guided. The supplied welding wire 20 protrudes from the power feed tip 38, and its tip 20a is shielded by the shielding gas. The welding current supplied from the welding power source 16 flows from the power feed tip 38 to the tip 20a of the welding wire 20 and generates an arc between the tip 20a of the welding wire 20 and the workpieces A, B, and C. The welding torch 36 moves along the welding lines L1 to L4, and welding is performed along the welding lines L1 to L4. In each of the welding lines L1 to L4, gas shield arc welding is performed over a predetermined period.

  The control device 14 is preliminarily taught instruction condition data 12 relating to welding performed on the workpieces A, B, and C. The instruction condition data 12 includes, for each of the welding lines L1 to L4, the locus of the welding line, the welding speed (the moving speed of the welding torch 36), the target value and normal range and allowable range of the welding current, and the target value and normal range of the welding voltage. And the permissible range, the normal range and permissible range of the wire feed force are described. These are called welding conditions. Here, the normal range of the welding voltage and the welding current is a range in which it can be determined that the welding has been performed almost as scheduled if the welding voltage and the welding current at the time of welding are within this range. In addition, if the welding voltage and welding current at the time of welding are within this range, the allowable range of welding voltage and welding current may be slightly different from the schedule, but it can be determined that welding satisfying the required joint strength has been performed. It is a range. The normal range of the wire feeding force is a range in which it can be determined that the welding wire 20 is normally fed if the wire feeding force is within this range. The allowable range of the wire feeding force is a range in which it is determined that it is not necessary to replace the conduit cable 34, the power feed tip 38, or the like, although the conduit cable 34, the power feed tip 38, or the like may be worn. In each index, the normal range is set narrower than the allowable range. These normal ranges and allowable ranges are described in FIG. 3, FIG. 4, FIG.

The control device 14 controls the operation of the robot 24 based on the trajectories of the welding lines L1 to L4 described in the instruction condition data 12, the welding speed, and the like. Thereby, the welding torch 36 moves along the welding lines L1 to L4 in the order of the welding lines L1, L2, L3, and L4.
The control device 14 controls the operation of the welding power source 16 based on the welding voltage target value described in the instruction condition 12, the operation of the robot 24 controlled by the control device 14, and the like. Thereby, while the welding torch 36 is moving along the welding lines L1 to L4, a welding voltage is applied between the power feed tip 38 of the welding torch 36 and the workpieces A, B, and C.
The control device 14 calculates the feeding speed of the welding wire 20 at which the target welding current is realized based on the welding current target value described in the instruction condition 12 and the like. Next, an operation command is given to the wire feeding device 32 based on the calculated feeding speed of the welding wire 20 and the operation of the robot 24 controlled by itself. Thereby, the welding wire 20 is fed to the welding torch 36 while the welding torch 36 moves along the welding lines L1 to L4.
The control device 14 stores equipment management information related to the welding equipment. The facility management information includes, for example, the date and time when the conduit cable 34 and the power supply chip 38, which are consumables, are replaced, and records relating to operation errors occurring in the robot 24 and the transfer device 48.
As described above, the control device 14 controls each device based on the instruction condition data 12. As a result, various welding indices at the time of welding are adjusted based on the instruction condition data.

Next, the monitoring processing device 50 will be described. The monitoring processing device 50 is configured using a general-purpose computer device. That is, the monitoring processing device 50 includes a processing device that executes various calculations and a storage device that stores various electronic data.
The monitoring processing device 50 can input from the control device 14 the instruction conditions described in the instruction condition data 12 and the command conditions instructed by the control device 14 to other devices. Thereby, for each of the weld lines L1 to L4, for example, the target value of the welding voltage, the normal range and the allowable range, the target value of the welding current, the normal range, the allowable range, and the like can be grasped.
Further, the monitoring processing device 50 can input command conditions and the like that the control device 14 has instructed other devices from the control device 14. Thereby, the monitoring processing apparatus 50 can grasp | ascertain the wire feeding speed etc. which were commanded to the welding lines L1-L4 currently welded, for example, the wire feeding apparatus 32, for example.
The monitoring processing device 50 can input facility management information from the control device 14.
In addition, the monitoring processing device 50 can input the measured welding voltage and welding current from the welding power source 16. The monitoring processing device 50 can measure the welding voltage and welding current over time during the period in which welding is being performed, using the measuring devices 42 and 44 of the welding power source 16.
Further, the monitoring processing device 50 can input the measured wire feeding force from the wire feeding device 32. The monitoring processing device 50 can measure the wire feeding force over time through the wire feeding device 32 during the period in which welding is performed.

The monitoring processing device 50 executes processing for monitoring welding performed by the welding device 10 based on the various input information described above. FIG. 2 is a flowchart showing a flow of processing executed by the monitoring processing device 50. Hereinafter, the processing executed by the monitoring processing device 50 will be described with reference to the flowchart shown in FIG. The monitoring processing device 50 repeatedly executes a series of processing flows shown in FIG. 2 together with a cycle in which the welding device 10 sequentially welds the welding lines L1 to L4 of the workpieces A, B, and C. .
In step S <b> 2 of FIG. 2, a weld line on which the welding apparatus 10 performs welding is specified. Specifically, it is specified which weld line (L1 to L4) of which workpiece (A, B, C) is to be welded. By specifying the welding lines L1 to L4 at which welding is performed, information for specifying the welding conditions of the welding to be performed can be obtained.
In step S4, the normal range of the welding index to be measured is set based on the weld line specified in step S2. Here, normal ranges of welding current, welding voltage, and wire feed force are set. FIG. 3 illustrates an example of the normal range CL to CU of the welding current C along with the temporal change of the welding current C during the welding execution period. FIG. 4 illustrates an example of the normal range VL to VU of the welding voltage V together with the temporal change of the welding voltage V during the welding execution period. FIG. 5 illustrates an example of the normal range 0 to FU of the wire feeding force F together with the temporal change of the wire feeding force F during the welding execution period.
In step S6, measurement of the welding index is started with a predetermined time delay from the time when the welding apparatus 10 starts welding. Here, measurement of welding current, welding voltage, wire feeding force, etc. is started. As shown in FIGS. 3, 4, and 5, each welding index changes in an unstable manner at the beginning or end of the welding execution period. By delaying the measurement start time of the welding index from the welding start time, the initial period of the welding execution period is not included in the measurement period Tm.

In step S8, it is determined whether or not the measured welding index is within a normal range. If the measured welding index is within the normal range, the process proceeds to step S12, and if the measured welding index is outside the normal range, the process proceeds to step S10. This step is determined for each of the welding current, welding voltage, and wire feed force.
In step S10, a process of measuring an abnormal period Tf in which the measured welding index is outside the normal range is performed. More specifically, the abnormal period Tf is cumulatively calculated by adding the determination cycle time Δt in steps S8 to S12 to the abnormal period Tf up to now. The abnormal period Tf is measured for each of the welding current, the welding voltage, and the wire feeding force.
In step S12, it is determined whether or not the measurement period Tm has elapsed since the measurement of the welding index was started (step S6). The measurement period Tm can be set in advance for each of the weld lines L1 to L4, for example. If it is before the measurement period Tm has elapsed (No), the process returns to Step S8. If the measurement period Tm has elapsed (Yes), the process proceeds to step S14.
The above-described determinations at steps S8 to S12 and the timing process are repeatedly executed every cycle time Δt. Thereby, for each welding index (welding current, welding voltage, wire feeding force), an abnormal period Tf in which the welding index is outside the normal range is counted.

In step S14, an abnormal period rate P that is a ratio of the abnormal period Tf to the measurement period Tm is calculated. That is, (abnormal period rate P) = (abnormal period Tf) / (measurement period Tm). The abnormal period rate P is calculated for each welding index (welding current, welding voltage, wire feeding force). The calculated abnormal period rate P is stored together with the corresponding weld line (by workpiece and by weld line). The monitoring processing device 50 stores and stores the welding line and the abnormal period rate P in association with each other for each welding performed sequentially by the welding device 10.
Here, the characteristics of the abnormal period rate P will be described. As shown in FIG. 3, for example, when the welding current C is measured over time over the welding execution period, a period G in which the welding current C changes slowly, a period H in which the welding current changes rapidly, and the like are observed. Is done. In the period G in which the welding current C fluctuates relatively slowly, even if the welding current C deviates from a target value (for example, the median value of the normal range), the welding current C deviates from the target value over a long period of time. There is a high possibility that defects will be included in the performed welding. On the other hand, in the period H in which the welding current rapidly fluctuates, even if the welding current C greatly deviates from the target value, the welding current C returns to the target value in a short period of time, so that there is little influence remaining on the performed welding. . Or the fluctuation | variation itself in the measured period H may originate in the noise etc. of a measuring device. Therefore, when monitoring the welding, it is preferable to detect the fluctuation as shown in the period G in FIG. 3 with high accuracy and overlook the fluctuation as shown in the period H in FIG.

  On the other hand, the abnormal period Tf changes sensitively with respect to the period G in which the welding current fluctuates slowly when the set range CL to CU of the normal range is changed, and the period H in which the welding current C fluctuates rapidly. Changes insensitive. For example, when the setting range CL to CU of the normal range is set to be narrow, the abnormal period Tf due to the period G in which the welding current fluctuates gently becomes long, while the abnormal period Tf due to the period H in which the welding current fluctuates rapidly is not much. It won't be long. As a result, the abnormal period rate P responds sensitively to the state to be detected (fluctuation in period G in FIG. 3) and insensitive to the state to be overlooked (fluctuation in period H in FIG. 3). To do. That is, the abnormal period rate P can be said to be an index that quantitatively indicates the quality of the welding performed. This can be said not only for the welding current C but also for other welding indices such as the welding voltage V and the wire feeding force F. The abnormal period rate P of the present example takes a larger value as welding is abnormally performed.

  In step S16, it is determined whether or not the calculated abnormal period rate P exceeds a predetermined determination reference value Pz for each welding index. If the abnormal period rate P exceeds the determination reference value Pz, it can be determined that the welding has been performed abnormally (or in a state conforming to the abnormality). The determination result of this step is displayed on the monitor 80 in a later step S22 and taught to an operator or the like. As the determination reference value Pz, a different value may be used for each welding index, or the same value may be used. When the calculated abnormal period rate P exceeds the predetermined determination reference value Pz (yes), the process proceeds to step S18. Otherwise (No), go to Step S22

In step S18, in response to the fact that the abnormal period rate P exceeds the determination reference value Pz in the current welding, is the stored abnormal period rate P at the previous welding stored exceeding the determination reference value Pz? Determine whether or not. That is, it is determined whether or not the abnormal period rate P has continuously exceeded the determination reference value Pz over the last two weldings. In this step, it is possible to determine whether or not the same determination is continued not only in the recent two times of welding but also in a number of times of welding.
The process of step S18 has two meanings. The first meaning is to increase the reliability of the determination result by determining that the same determination is continued. In this case, for example, even when the setting range of the normal range is set to be narrower, accurate determination can be performed while reducing the influence of noise or the like.
The second meaning is to determine whether the abnormal period rate P is rising at the specific welding lines L1 to L4 or is rising regardless of the welding lines L1 to L4. In the latter case, for example, it is estimated that an abnormality has occurred in the welding apparatus 10. As shown in FIG. 6, for example, as the power supply tip 38 wears, the abnormal period rate P of the welding current C gradually increases. In such a case, the abnormal period rate P continuously exceeds the determination reference value Pz from a certain welding time. In the case shown in FIG. 6, the abnormal period rate P continuously exceeds the determination reference value Pz from the time of welding of the weld line L3 of the workpiece B. By the process of step S18, it can be detected that an abnormality has occurred in the welding apparatus 10.

In step S20, in response to the fact that the abnormal period rate P for the current welding exceeds the determination reference value Pz, the stored abnormal period rate P for the welding for the same weld line of the previous time exceeds the determination reference value Pz. It is determined whether or not. For example, if the current determination is for the weld line L1 of the workpiece B, the stored abnormal period rate P for the weld line L1 of the workpiece A is determined. Thereby, it is possible to determine whether or not the abnormal period rate P has continuously exceeded the determination reference value Pz in the welding to the same weld line twice (two workpieces) recently. In addition, you may determine whether it is continuing about the same weld line not only twice recently but many times (multiple workpiece | work).
By the process of step S20, it is determined whether or not it is determined that there is an abnormality only in specific welding lines L1 to L4. By this determination, it can be determined whether or not it is determined that there is an abnormality with respect to welding performed under specific welding conditions. As shown in FIG. 7, for example, only in the weld line L2, the abnormal period rate P may repeatedly exceed the determination reference value Pz. Such a phenomenon may have a problem in setting welding conditions for the weld line L2. The problem of the welding conditions is not limited to setting values such as a welding current and a welding voltage, but includes, for example, the setting of the locus of the welding line L2 taught to the robot 24. Or the setting regarding the positioning of each part 101-104 in each workpiece | work A, B, C is also included. Since the cause of the abnormality is greatly different between the state shown in FIG. 6 and the state shown in FIG. 7, it is preferable to distinguish the state shown in FIG. 6 from the state shown in FIG. The process of step S20 is equivalent to evaluating the abnormal period rates P arranged simply in the welding order as shown in FIG. 7 in accordance with the welding lines L1 to L4 as shown in FIGS. 8 (a) to 8 (d).

  In step S22, the determination results in steps S16, S18, and S20 are displayed on the monitor 80. For example, in the determination in step S16, “Yes” is displayed if yes, and “Normal” is displayed if no. Furthermore, if the determination in step S18 is yes, for example, “Needs inspection” is displayed. At this time, for example, equipment management information input from the control device 14 may be taken into account. For example, when a considerable period has elapsed since the power supply tip 38 has been replaced and it is determined that “inspection is required” based on the welding current C, a display prompting replacement of the power supply tip 38 may be displayed. If the determination in step S20 is yes, the corresponding welding line L2 may be displayed to prompt review of the welding conditions.

Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.
As shown in FIG. 9, for example, when measuring an abnormal period, the measured welding index (welding current C in FIG. 9) is lower than the lower limit CL of the normal range and exceeds the upper limit CU of the normal range. The time period may be distinguished from the period Tb, and the abnormal period rate may be calculated for each of the periods Ta and Tb. The fluctuation of the welding index due to the problem of the welding apparatus 10 or the like is determined in one direction according to the cause. On the other hand, fluctuations caused by noise or the like often increase or decrease the measured value of the index. Therefore, for example, by calculating the difference between the abnormal period rates of both, the influence caused by the noise can be grasped, and the determination can be made with the influence of the noise removed further.
Moreover, when determining the calculated abnormal period rate, a second determination reference value may be set, and the determination for the abnormal period rate may be performed in two stages. Since the abnormal period rate is an index that quantitatively indicates the quality of welding, it is possible to take measures before the welding is performed in an abnormal state.
Alternatively, the abnormal period rate for each welding index may be integrated and the quality of welding may be determined based on the integrated abnormal period rate. When the abnormal period rate for each welding index is integrated and calculated, each abnormal period rate may be weighted based on the correlation between the welding indices.

  The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

The figure which shows the welding process of an Example typically. The flowchart which shows the flow of the operation | movement which a monitoring processing apparatus performs. The figure which shows the time change of the welding current in the welding implementation period. The figure which shows the time change of the welding voltage in a welding implementation period. The figure which shows the time change of the wire feeding force in the welding implementation period. The figure which shows the abnormal period rate which increases with the frequency | count of welding implementation in order of welding implementation. The figure which shows the abnormal period rate which increases in a specific weld line in order of welding implementation. The figure which shows the abnormal period rate which increases in a specific weld line according to a weld line. The figure which shows another example of the time measuring method of an abnormal period.

Explanation of symbols

10 .. Welding device 12 .. Indicating condition 14 .. Control device 16 .. Welding power supply 20 .. Wire 20 a for welding .. Wire tip 22 .. Gas cylinder 24 .. Industrial robot 32. 36..Welding torch 38..Feed tip 42..Current measuring device 44..Voltage measuring device 48..Conveying device 50..Monitor processing device 80..Monitor 101, 102, 103, 104..Parts A and B , C. Work (car body)
L1, L2, L3, L4 ... Welding line

Claims (4)

A device for monitoring the quality of welding that is repeatedly performed while switching welding conditions ,
In each of the weld, measuring means for periodically measured contact Keru welding indicators measurement period in the welding operation,
A time measuring means for measuring a period in which the measured welding index is within a predetermined index range determined for the welding conditions at that time ;
A calculation means for calculating a period ratio between the timings with respect to the measurement period;
An accumulation storage means for accumulating and storing the period rate calculated by the calculation means in combination with information capable of specifying the welding conditions at that time;
A first determination for determining whether or not the period rate calculated by the calculation means is within a predetermined abnormal range is performed , and when it is determined that the period rate is within the abnormal range in the first determination, Determination means for further executing a second determination for determining whether or not a period rate at the time of the last welding performed under the same welding conditions stored is within the abnormal range ;
Based on the determination result of the determination means, when it is determined that the period rate is continuously within the abnormal range in a plurality of times of welding under the same welding condition, a display that displays information that can specify the welding condition Means,
A monitoring device comprising: When the determining means determines that the abnormality is in the abnormal range in the first determination, the period rate at the time of the last performed welding stored in the storage means regardless of welding conditions is the abnormal range. And further executing a third determination for determining whether or not
The display means, based on the determination result of the determination means, when it is determined that the period rate is continuously within the abnormal range in a plurality of times of welding regardless of welding conditions. The monitoring apparatus according to claim 2, further displaying information for prompting inspection . A method for monitoring the quality of welding that is repeatedly performed while switching welding conditions ,
In each of the welding, a step of periodically measured contact Keru welding indicators measurement period in the welding operation,
A step of measuring a period in which the measured welding index is within a predetermined index range determined for the welding conditions at that time ;
Calculating a period rate between the timings with respect to the measurement period;
A step of accumulating and storing the calculated period rate in combination with information capable of specifying the welding conditions at that time;
While performing the 1st determination which determines whether the calculated period rate exists in the predetermined | prescribed abnormal range, when it determines with being in the said abnormal range in 1st determination, it is on the same welding conditions memorize | stored. A determination step of further executing a second determination for determining whether or not a period rate at the time of the last welding is within the abnormal range ;
Based on the determination result of the determination step, when it is determined that the period rate is continuously within the abnormal range in multiple times of welding under the same welding condition, a display step for displaying information that can specify the welding condition When,
A monitoring method comprising: In the determination step, when it is determined in the first determination that it is within the abnormal range, whether or not the last-performed welding time rate is within the abnormal range regardless of welding conditions. Further performing a third determination to determine whether
In the display step, based on the determination result of the determination step, when it is determined that the period rate is continuously within the abnormal range in a plurality of times of welding regardless of welding conditions, 4. The monitoring method according to claim 3, further comprising displaying information for prompting inspection.

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