JPS61199578A - Welding monitoring device in arc welding robot - Google Patents

Abstract

PURPOSE:To perform automatically the judgement of whether the measurement of current and voltage and the values are within proper range or not by comparing the upper limit value and lower limit value of which the arithmetic mean value of the measured value of welding current and voltage is set in advance and by alarming the abnormality in case of exceeding the range. CONSTITUTION:The current and voltage of arc welding circuit are measured by each measuring circuit 5, 6 via each input circuit 3, 4 on each preset sampling period with the input of the signal transmitted from a measuring conditions setting circuit 7 at welding work time. The arithmetic mean value of the respective measured value is calculated by arithmetic circuits 8, 1 and discriminated with comparing by means preset upper and lower limit values and comparison discriminating circuits 10, 11. In case of the mean value being within the range of the upper and lower limit values, the welding state is taken as good and the output signal of the abnormality is not inputted in an abnormality alarming device 14 or the display of normality is held. On the other hand, the abnormal signal is inputted in the abnormality alarming device 14 in case of the mean value exceeding the upper and lower limit values and it is displayed by a lamp buzzer, etc. or recorded by a printer, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a welding monitoring device for a teaching playback type arc welding robot, and more particularly to a welding monitoring device for determining the suitability of welding conditions.

Consumable electrode type arc welding, such as open CO2 welding, MIG welding, and MAG welding, has traditionally been performed semi-automatically, but recently, due to improvements in productivity, it has become more common to use 7-way welding robots. It's coming. FIG. 4 shows an outline of the general system and welding circuit of this arc welding robot.

Note that the jig, jig control panel, shield gas, etc. are omitted in this figure. The welding torch 31 is attached to the wrist 32a of the robot 32, and when the torch 31 comes to the welding location due to the operation of the robot 32, a signal to start welding is sent from the robot control panel 34 to the welding power supply 35, and the wire 36 is fed to the torch 31 by the wire supply roller 37, an arc is generated between the wire 36 and the workpiece (base metal) 38, and a DC current flows through the welding circuit to perform welding. , 39.40 are welding cables on the positive and negative sides, 41.42 are ammeter and voltmeter, respectively.
43 is a welding command cable, and 44 is a robot control cable. In the above-mentioned arc welding robot, several welding points are generally welded consecutively within one operation cycle. This may include cases in which there are several different welding points within one object to be welded, or cases in which there are several objects to be welded and a large number of welding points. Furthermore, the welding conditions for each welding location are often not the same.

Therefore, various welding conditions were considered in order to perform welding with stable quality at each of these welding locations. That is, in general, in arc welding, the quality of the welded part is greatly influenced by welding conditions such as welding current, welding voltage, and welding speed, and the suitability of the welding state is determined based on these conditions. Therefore, in the teaching playback type arc welding robot, a command value corresponding to the output is given in advance so that an appropriate condition value is output for each welding location. Among the above welding conditions, once the welding speed is set to an appropriate value, it does not change because it is determined by the operating speed of the robot itself. Therefore, the welding current and welding voltage are 1lill between the tip of the torch 31 and the workpiece 38.
It often fluctuates due to i or other causes, and when the fluctuation is large, welding defects such as insufficient leg length and burn-through may occur.

Therefore, the operator can read the current and voltage during welding with the naked eye using the ammeter 41 and voltmeter 42 of the welding power source 35 and determine whether the welding conditions are within appropriate ranges. was judging.

However, in robot welding, several welding points are welded in succession, so the welding current and voltage change sequentially, and errors in reading are likely to occur, especially when the values at points where welding time is short. had a large error.

Further, even if the values were read and recorded, when there were a large number of welding locations, it was difficult to immediately determine whether the measured values at each welding location were within the appropriate range.

For this reason, welding robot operators are unable to accurately monitor welding conditions and cannot control welding conditions during welding, so they must inspect all welded areas for quality after welding is complete. The reality is that a large amount of time is wasted on this.

Therefore, an object of the present invention is to provide a welding monitoring device for an arc welding robot that can automatically measure the current and voltage of an arc welding circuit and determine whether the measured values are within the appropriate range. −? In order to achieve the above object, the present invention provides the following methods for each welding location:
The welding robot operator is configured to be able to simply determine whether there is an abnormality in the welding condition without having to measure the welding current and voltage and determine whether these measured values are within the appropriate range. did. In other words, the arithmetic mean value of the measured values measured by the welding current measuring circuit and the welding voltage side constant circuit, which measures the welding current and the contact voltage at a given time at predetermined time intervals for each welding location, respectively, and the welding voltage side constant circuit. each arithmetic circuit that respectively calculates the arithmetic mean value, each comparison and discrimination circuit that compares and discriminates the arithmetic mean value calculated by each of the arithmetic circuits with preset upper and lower limit values, and each comparison and discrimination circuit that makes a comparison and discrimination. In addition, an abnormality warning device is provided which indicates an abnormality in the welding condition when the arithmetic mean value exceeds the range between the upper limit value and the lower limit value in at least one of the comparison and discrimination circuits.

In addition, according to the above configuration, during welding work i using a teaching playback type arc welding robot that continuously welds multiple locations, the welding current and welding current of the arc welding circuit are measured by each of the measurement circuits. The voltage is measured, each measured value is calculated by each arithmetic circuit to calculate an arithmetic average value, and each comparison judgment circuit determines whether each arithmetic average value is within the range of each upper and lower limit value. Therefore, in the comparison/discrimination circuit for either the welding current or the welding voltage, or both, when the above-mentioned W, operative mean value exceeds the range between the upper limit value and the lower limit value, the abnormality alarm device notifies the operator of an abnormality in the welding condition. The operator does not have to read the values of the ammeter and voltmeter with the naked eye and judge whether they are within the appropriate range, but simply check whether the abnormality alarm device indicates an abnormality or not. It is only necessary to make a judgment, and it becomes clear whether or not a welding defect has occurred or where the defect has occurred, and the time required to judge whether or not the welding condition is appropriate can be greatly shortened. In addition, the welding current
Since the measured voltage values are averaged once and then compared with the upper and lower limit values, it is possible to reliably judge the suitability of the welding condition even if the welding current and voltage fluctuate momentarily or where the welding time is short. . Furthermore, upper and lower limit values can be set in advance in the upper and lower limit setting circuits for each welding location, and these upper and lower limit values can be compared with the average values of welding current and voltage using each comparison discrimination circuit. , can be well applied to robot welding.

In other words, with conventional welding monitoring devices, the upper and lower limits for welding current and voltage can only be set for each condition, or the welding current and voltage to be measured cannot be averaged. Therefore, it could not be applied to robot welding, where the welding conditions for each welding location often differ.

EXAMPLES Below, the present invention will be specifically explained based on illustrated examples.

FIG. 1 shows a block diagram of a welding monitoring device according to this embodiment. In the figure, reference numeral 1 denotes a welding power source, whose positive output terminal is connected to the wire of a welding torch, while its negative terminal is connected to the workpiece through a shunt 2. The flow divider 2 includes:
A welding current input circuit 4 is connected, and a measuring circuit 6 measures the welding current of the arc welding circuit. A welding voltage input circuit 3 is connected between the output terminals of the welding power source 1, and a measuring circuit 5 measures the welding voltage of the arc welding circuit.

A measurement condition setting circuit 7 is connected to both measurement circuits 5 and 6, which input measurement signals for carrying out measurement at a predetermined time and for a predetermined time. In this circuit 7, since the input to each input circuit 3.4 is unstable at the start of welding, measurement is not performed at the same time as the input, but after a certain period of time (escape time), each measurement is started, and the input to each input circuit 3.4 is unstable. A measurement signal is input to each measurement circuit 5.6 so that measurement is performed only within a measurement time preset at a measurement interval (sampling period). The escape time (e.g. 0.5 seconds), measurement interval (e.g. 0.1 seconds) and measurement time are set in advance in the condition setting circuit 7 for each welding location. and the measurement condition setting circuit 7 constitute a current measuring device 16, and the welding voltage input circuit 3, measuring circuit 5 and measurement condition setting circuit 7 constitute a voltage measuring device 15. The above measurement circuits 5 and 6 are equipped with air filters, 9h, and
Rffll'if I performs an operation to calculate the arithmetic mean by dividing the γ of one stroke by the number of measurements. A comparison/discrimination circuit 10.11 is connected to each arithmetic circuit 8, 9, and an upper/lower limit setting circuit 1
In step 2.13, the predetermined upper and lower limit values and the above measured value, that is, the arithmetic mean value are compared and determined. An abnormality alarm device 14 that indicates an abnormality is connected to this comparison/discrimination circuit 10゜11, and when the above-mentioned measured value exceeds the upper and lower limit range, it is displayed with a lamp, buzzer, etc., or recorded on a printer, etc. By recording and recording, the welding robot operator is informed of abnormalities due to changes in welding conditions, that is, locations with welding defects.

Note that the process from inputting current and voltage to displaying abnormalities is performed sequentially for each welding location, and the calculation processing and comparison judgment are completed by the time the input signal to start welding is received for the next welding location. ing. Furthermore, when the measurement at the n-th welding point is completed in one cycle of robot operation, the circuit automatically returns to the first welding point.

FIG. 2 shows a time chart of one cycle of robot operation when welding is performed using an arc welding robot. In this figure, En (V) and In (A) are symbols indicating the welding voltage and welding current at the n-th welding point, respectively, and tn (seconds) is the arc time.

FIG. 3 shows the relationship among welding time, arc time, escape time, and measurement time.

At the start of welding (when arc occurs), the welding voltage and welding current are unstable, so there is an escape time in which no measurements are made, but since they are similarly unstable at the end of welding (when arc ends), The measurement time is determined so that the measurement is not performed even at the end of the measurement.

Therefore, the sum of the escape time and the open time during measurement is shorter than the welding time (the time during which the welding command is ON).

The welding time is the robot operating time between the welding start point and end point, plus the hot start time (welding start point) and crater processing time (end point), if any. The time can be easily determined from the display on the robot control panel.

In addition to starting the measurement by detecting the generation of welding voltage as described above, the measurement can also be started by detecting a welding ON signal from an external output contact such as a robot control panel.

According to the above configuration, during welding work using a teaching playback type 7-way welding robot that continuously welds multiple locations, it is detected that welding has started due to the generation of welding voltage, etc., and after escape time, By inputting signals from the measurement condition setting circuit 7, the current and voltage of the arc welding circuit are measured within a set time at each sampling period set in advance by each measurement circuit 5.6 via each input circuit 3゜4, and calculated. The arithmetic mean value of each measured value is calculated in the circuit 8.9, and each preset upper and lower limit value and each average value are compared and determined in the comparison/discrimination circuit 10.11. If the average value is included, it means that the welding conditions, that is, the welding state, are good, and the output signal indicating that there is an abnormality is not input to the abnormality alarm device 14, or the device 14 indicates that it is normal. Alternatively, while printing and recording, if the average value exceeds the upper and lower limit values, it means that the welding conditions, that is, the welding state, are abnormal, and a signal indicating the abnormality is input to the abnormality alarm device 14, and a lamp, Display it with a buzzer, etc. or record it with a printer, etc.

According to the above embodiment, even when several welding points are welded in succession, the welding current and voltage can be continuously and automatically measured for each welding point by the measuring circuits 5 and 6, and each measurement It calculates the arithmetic average value of the values, compares and determines whether this average value is within a predetermined upper and lower limit range, and displays or records the result, or both. Even if the welding current and voltage fluctuate momentarily, the average value of the current and voltage can be reliably detected even in places where the welding time is short, and it is possible to detect whether the welding condition is appropriate, that is, whether or not a welding defect has occurred, or whether a welding defect has occurred. This makes it possible to greatly shorten the detection time and prevent welding defects from being sent to the next process or being sold as products on the market.

In addition, with conventional welding monitoring devices, the upper and lower limits can only be set under one condition, or the welding current and voltage to be measured cannot be averaged. It could not be applied to the case of robot welding, which is often different. However, according to the above embodiment, the upper and lower limit values can be set in advance for each welding location by the upper and lower limit value setting circuits 12 and 13,
Moreover, the averaging process of welding current and voltage can be performed by each arithmetic circuit 9, 8, so that it can be fully applied to robot welding.

Furthermore, since welding robots simply perform repeated welding according to input commands, in order to obtain a good welded product, welding robots must be optimized before welding so that the appropriate welding current and voltage are output for each welding location. A command value must be given. For this purpose, it is necessary to understand the relationship between the command value and the welding current or voltage in advance, or to check whether the target current or voltage is being outputted with respect to the input command value. Even in such a case, if the welding monitoring device according to this embodiment is used, the optimum command value and welding conditions can be accurately and easily grasped and set.

Note that the equipment, parts, etc. constituting this device may be existing ones, and there is no need for anything specifically limited to this device.

[Brief explanation of the drawing]

Figure 1 is a block diagram of a welding monitoring device according to the present invention, Figure 2 is a block diagram of a welding monitoring device according to the present invention;
The figure is a welding time chart of the above device, Figure 3 is a diagram showing the relationship between welding time, escape time and measurement time, and Figure 4 is a diagram showing the relationship between welding time, escape time and measurement time.
The figure is a schematic diagram of a conventional general welding robot system and welding circuit. 1... Welding power source, 3... Welding voltage input circuit, 4
...Welding current input circuit, 5,6...Measurement circuit,
7...Measurement condition setting circuit, 8.9...Arithmetic circuit, 10.11...Comparison/discrimination circuit, 12.13...
- Upper and lower limit value setting circuit, 14... Abnormality alarm device, 15
．． 16...Measuring device. Patent Applicant: Tokai Rika Denki Seisakusho Co., Ltd. Agent Patent Attorney: Aoyama Baka 2 May 24, 1985 Patent Application No. 039524 No. 2, Title of Invention: Welding Monitoring Device for Arc Welding Robot 3, Amendments Patent applicant address: 4 Toyota Unoda II, Oguchi-cho, Niwa-gun, Aichi Prefecture, agent address: 5, Honmachi Building, 2-10 Honmachi, Higashi-ku, Osaka-shi, Osaka Prefecture;
Date of amendment order: Invention specification: “Detailed description of the invention”, “With drawings! Bego EqQ
) 6. Fields to be corrected. drawing. 7. Contents of amendment A. The following parts of the description will be corrected. (1) Page 7, line 17, [Correct "Once" and "□" to "Once." (2) On page 8, line 17, ``wire of welding torch'' should be corrected to ``welding torch.'' (3) Page 8, line 19, page 9, line 15 to 166
Go to the next line and correct "Welding current input circuit 4" to "Welding current input circuit 3". (4) On page 8, line 20, and page 9, line 16, correct the text "Measuring circuit 6" to "Measuring circuit 5." (5) On page 9, line 2, from line 17 to line 188, [Welding voltage input circuit 3] has been corrected to "Welding voltage input circuit 4." (6) From the 2nd line to the 3rd line on page 9, and the 18th line
On the line, ``Measuring circuit 5'' should be corrected to ``Measuring circuit 6''. (7) On page 9, line 15, ``Set above'' should be corrected to ``Set above.'' (8) On page 9, lines 16 to 177, "Current measuring device 16" is corrected to "Current measuring device 15J." (9) Page 9, lines 18 to 199 Please correct the text "Voltage measuring device 15J" to "Voltage measuring device 16J." 8, 9” and correct it. (11) From page 15, line 8 to line 9, [3.
...Welding voltage input circuit, 4...Welding current input circuit" should be corrected to "3...Welding current input circuit, 4...Welding voltage input circuit". Of the 83 drawings, Figures 1 and 4 will be corrected as shown in the attached sheet. that's all

Claims (1)

[Claims] (1) During welding work using a teaching playback type arc welding robot that continuously welds multiple locations, the welding current and welding voltage of the arc welding circuit are measured and each measured value is within a preset range. A welding monitoring device for an arc welding robot that determines the suitability of the welding condition by determining whether or not the welding condition a calculation circuit that calculates the arithmetic average value of the measured values measured by each of the measurement circuits, and a preset upper and lower limit value for the arithmetic average value calculated by each of the calculation circuits. When the arithmetic mean value exceeds the range of the upper limit value and lower limit value in at least one of the above comparison and discrimination circuits, the welding state is determined. 1. A welding monitoring device for an arc welding robot, comprising: an abnormality warning device that indicates an abnormality.