JPH11123548A - Method for judging stability of welding at end treated part of arc welding and device for judging stability - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the flowing of welded defective by judging whether or not the stability of welding phenomenon in the treated part at the end part of arc welding is good. SOLUTION: This device transmits analog signals by detecting the welding current and the welding voltage with detecting means 7, 8. Each analog signal is made to a digital signal by sampling with an A/D converter 9. Based on these digital signal, arbitrary one item or more among welding current integral value standard deviation during arc in one period, welding current integral value standard deviation during short circuit in one period, and arc/short circuit time ratio standard deviation in one period with a CPU 10, are calculated. When the different between the calculated value of any item and the corresponding reference value exceeds the permissible range, it is judged than welding is unstable or defective and the result is displayed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a consumable electrode type gas shielded arc welding, and aims at preventing outflow of poor welding quality caused by instability of welding phenomena in a terminal processing part. And a method for determining welding stability.

[0002]

2. Description of the Related Art In consumable electrode type gas shielded arc welding, the output control of a welding power source is changed from a thyristor type to an inverter type due to the progress of control elements, and the control speed is 30%.
The speed is increased about 50 to 200 times from 0 Hz to 15 to 60 KHz, and the waveform of the welding current can be controlled, improving arc start performance, improving the stability of welding phenomena in high-speed welding, and reducing the amount of spatter generated. In addition, it is possible to reduce the diameter of the spherical mass at the tip of the welding wire for improving the arc starting property, and the stability of the welding phenomenon is being improved.

[0003] However, the welding quality of the terminal processing section is liable to cause various abnormal phenomena due to the inertia of the wire feeding mechanism, which has been a major problem in an automatic welding line using a welding robot or the like. The determination of the quality of the stability of the welding phenomena of the terminal processing portion is generally performed by an operator or a technician by visually observing the uniformity of the weld bead appearance of the terminal processing portion.

[0004] However, due to the qualitative determination by visual observation, there is an individual difference in the determination in the case of a minute abnormality, and it has been difficult to find a uniform standard for in-line determination.

[0005]

At present, there is no method for real-time and quantitative monitoring of the stability of the welding phenomena in the terminal processing section in real time. These countermeasures have been taken after replacing a wire conduit cable, replacing a contact tip, or an abnormal welding quality. The present invention has been made in view of the above-described problems of the related art, and has as its object to provide a method and an apparatus that accurately grasp a welding phenomenon of a termination processing portion and quickly determine whether or not the stability of the welding phenomenon is good. I do.

[0006]

In order to achieve the above object, an object of the present invention is to provide an arc welding stability in a consumable electrode type gas shielded arc welding in which welding is performed while alternately repeating a short circuit and an arc. When determining, the analog output signal output using voltage detection means for detecting the welding voltage between the welding wire and the material to be welded, and current detection means for detecting the welding current flowing between the welding wire and the material to be welded The following three items are converted into digital signals at a predetermined sampling frequency and input to the arithmetic means to indicate the degree of welding stability of the termination processing unit. (A) Standard deviation of the welding current integral during the arc period for each cycle σ (∫I _An dt) (b) Standard deviation of welding current integral during short-circuit period for each cycle σ (∫I _Sn dt) (c) Standard deviation of arc / short-circuit time ratio for each cycle σ (T _An / T _Sn) One or two or more items are calculated and compared with the corresponding reference values, and when any one of the differences from the reference value exceeds a predetermined allowable range, the welding of the termination processing part is performed. This is a method for determining welding stability of an arc welding termination processing unit, which determines that the welding is unstable or defective.

A second aspect of the present invention is a consumable electrode type gas shielded arc welding end processing section arc welding stability determining apparatus for performing welding while alternately repeating a short circuit and an arc, comprising a welding wire and a material to be welded. Voltage detecting means for detecting a welding voltage between the two, current detecting means for detecting a welding current flowing between a welding wire and a workpiece, an A / D converter for converting an analog output signal from both means into a digital signal, Based on the digital signal from the converter, (a) the standard deviation of the welding current integral during the arc period every cycle σ (∫I _An dt) (b) the standard deviation of the welding current integral during the short circuit period every cycle Calculating means for calculating any one or more of three items of standard deviation σ (T _An / T _Sn ) of the ratio of arc / short-circuit time for each period, σ (∫I _Sn dt); Performance from arithmetic means Arc welding, comprising: a comparator for comparing the result with a preset reference value to determine whether a difference from the reference value is within an allowable range; and a display for displaying an output of the comparator. It is a welding stability determination device of a termination processing unit.

[0008]

The degree of stability of welding phenomena caused by the arc discharge not being formed stably in the termination processing unit is defined as the standard deviation of the integrated welding current value of the arc period for each cycle,
One or two or more of the three items of the standard deviation of the welding current integral value of the short-circuit period for each cycle and the standard deviation of the arc / short-circuit time ratio for each cycle are calculated and displayed as quantitative values, respectively. Is compared with the reference value, and when any one of the quantitative values exceeds a predetermined allowable range, it is determined that the welding phenomenon is unstable. By doing so, abnormal welding quality due to welding phenomenon instability due to poor power supply to the welding wire or increased feed resistance can be detected accurately and reliably.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of an embodiment of the present invention. Reference numeral 1 in the figure denotes a welding power source that applies a predetermined current and voltage between the welding wire 2 and the workpiece 5.
The welding wire 2 is fed at a predetermined speed by a feed roller 3 to weld the workpiece 5. 4 is a contact tip, 6 is a shunt for measuring a welding current, 7 is a current detection circuit for detecting a welding current flowing through a welding wire and a workpiece, and 8 is a welding voltage between the welding wire and the workpiece. 9 is an A / D converter for converting each analog output signal from both detection circuits 7 and 8 into a digital signal at a predetermined sampling frequency, and 17 is an arithmetic and output device for both detection circuits 7, 8 and A / D converter 9 is included.

The present apparatus 17 measures the welding voltage and welding current and converts them into digital values. The standard deviation of the arc period welding current integral and the standard deviation of the short-circuit period welding current integral for each cycle,
In addition, various calculations are performed to calculate the standard deviation of the arc / short-circuit time ratio for each cycle, and the calculation results are compared with a preset reference value to determine whether a difference from the reference value is within an allowable range. , A CRT 11 (display) and a printer 15 for displaying and printing their operation data, memories (ROM 12 and RAM 13) for storing various data necessary for programs and operations, constants necessary for measurement, and other information. A keyboard 14 for inputting data,
Further, the display unit 16 is configured to display an abnormal signal such as an abnormal welding current integrated value or an abnormal arc / short-circuit time ratio.

Next, a method for determining the stability of welding phenomena in the terminal processing section according to the present invention will be described. First, FIG. 2 shows a schematic processing flow of execution of the arc discharge state analysis of the termination processing unit. First, sampling rate, trigger level, arc
The short-circuit judgment voltage is input from the keyboard 14 and the CPU 10
Set within and start welding. When the welding voltage reaches the trigger level, input of the welding voltage / current is started, and data is stored in the RAM 13 until the number of measurements reaches the set number. When a predetermined number of samplings are completed, the ROM 12
By implementing the program stored in the
Performs various calculations.

Here, for various calculations, the setting of the calculation section can be input from the keyboard 14 in order to prevent erroneous determination of the calculation data. In other words, the arc start and the steady part can be excluded from the calculation section. When the calculation is completed, the various calculation results are compared with the corresponding reference values, and when any one of the quantitative values exceeds the preset allowable range, the welding phenomenon becomes unstable. Then, an abnormal signal such as an abnormal welding current value or an abnormal arc / short-circuit time ratio is output, and an abnormal welding quality such as irregular bead shape, undercut, burn-through, etc. is determined. When the arc discharge is formed stably, an OK signal is output.

Next, arc period melting in subroutine 1 in FIG.
The calculation of the integral value of the contact current will be described. Figure 3 is the arc period
Subroutine for calculating the standard deviation of the welding current integral value during welding
It is the details of. Performance of the standard deviation of the arc period welding current integral
The arithmetic is T₁After the time is up, set time T_TwoUntil
Current and welding voltage flowing between welding wire and workpiece to be welded
Is sampled, and the welding voltage in the n-th cycle reaches Va or more.
The measurement of the welding current is started from the time when
Calculates the welding current integral during the arc period up to the time
Then, the standard deviation of the integrated value is calculated. In addition,
Discrimination voltages Va and T ₁, T_TwoTime settings can be changed freely
I am able to do it.

The arc period welding current integral value, as shown in FIG. 6, represents an arc period welding current waveform for each cycle and an area ∫I _An dt surrounded by the arc time, and its standard deviation σ (∫I _An dt) simultaneously represents variations in welding current and arc time during the arc period. The fact that the standard deviation of the welding current integral becomes large means that the droplet transfer phenomenon is unstable due to the occurrence of an instantaneous arc in which the short-circuit phenomenon almost continues or a long-term arc phenomenon that does not lead to a short circuit. The lower the standard deviation, the more stable the droplet transfer phenomenon.

Here, in order to reduce changes in the standard deviation due to sampling noise, chattering, etc., an arc phenomenon within 1 msec is calculated as a short circuit time. This welding current integral standard deviation is compared with a reference value, and when the difference from the reference value exceeds a predetermined allowable range, an abnormal signal is output as an arc period welding current integral value abnormality.

Next, the calculation of the integrated value of the welding current during the short circuit in subroutine 2 in FIG. 2 will be described. FIG. 4 shows details of the subroutine for performing the welding current integral standard deviation calculation processing during the short circuit period. The calculation of the welding current integral standard deviation during the short circuit is
From time T ₁ after the time-up is a steady welding measurement start time, the welding current and welding voltage flowing between the welding wire and material to be welded set up time T ₂ is a steady welding measurement end time sampling, n-th cycle of The welding voltage V (n)
The measurement of the welding current is started from the time when the voltage has reached the short-circuit judgment voltage Va or less, the welding current integral value of the short-circuit period up to the time when the voltage has exceeded Va is calculated, and then the standard deviation of the integrated value is calculated. The setting of the judgment voltage Va and the times T ₁ and T ₂ can be arbitrarily changed.

The short-circuit time welding current integral value represents a welding current waveform of a short-circuit period for each cycle and an area ΔI _Sn dt surrounded by the short-circuit time as shown in FIG. _Sn dt) simultaneously represents the welding current during the short circuit period and the variation in the short circuit time.

The fact that this standard deviation becomes large means that
The short-circuit phenomenon is unstable due to the occurrence of an instantaneous short-circuit or a short-circuit phenomenon where the droplet transfer hardly occurs, and the short-circuit phenomenon is not released.The lower the standard deviation, the more stable the short-circuit phenomenon and the periodic transfer of the droplet Indicates what is happening.

Here, in order to reduce the change of the standard deviation due to sampling noise and chattering, a short circuit phenomenon within 1 msec is calculated as an arc time. This short-circuit period welding current integral standard deviation is compared with a reference value, and when the difference from the reference value exceeds a preset allowable range, an abnormal signal is output as a short-circuit period welding current standard deviation abnormality.

Next, the calculation of the standard deviation of the arc / short circuit time ratio in subroutine 3 in FIG. 2 will be described. FIG. 5 shows the details of the subroutine for performing the standard deviation calculation processing of the arc / short circuit time ratio. The calculation of the standard deviation of the arc / short-circuit time ratio is performed after a time-up time of T ₁ , and a set time T _2.
The welding current and the welding voltage flowing between the welding wire and the material to be welded are sampled, and the measurement of the arc time T _An starts from the time when the welding voltage V (n) in the n-th cycle reaches Va or more, and Va or less. Arc time up to the time when
The measurement of the short-circuit time T _Sn is started from the time when the welding voltage V (n) in the cycle reaches Va or less, the short-circuit time until the time when the voltage rises above Va is measured, and the arc / short-circuit time ratio is calculated. Thereafter, the standard deviation σ (T _An / T _Sn ) of the arc / short-circuit time ratio for each cycle is calculated.

The fact that the standard deviation of the arc / short-circuit time ratio is large means that the droplet transfer phenomenon due to the occurrence of an instantaneous arc, a long-term arc, an instantaneous short-circuit, a long-term short-circuit, etc. is unstable, and the standard deviation is low. It shows that the droplet transfer phenomenon is more stable. The standard deviation of the arc / short circuit time ratio is compared with a reference value, and when the difference from the reference value exceeds a predetermined allowable range, an abnormal signal is output as an arc / short circuit time ratio abnormality.

As described above, the monitoring of the welding quality abnormality is performed only in the terminal processing part excluding the arc start part and the steady welding part. The processing in the welding terminal part is such that the welding wire is attenuated by a specific time constant. This is because the welding phenomenon tends to become unstable because the coasting portion is melted, and the determination cannot be made based on the criterion for the steady welding portion. Therefore, according to the present embodiment, when the welding phenomenon is stably formed in the termination processing section, the abnormal signal is not output. For this reason, in the automatic and semi-automatic arc welding equipment, the output of the abnormal signal enables the worker or the engineer to easily detect the unstable state of the welding phenomenon in the terminal processing section, and the abnormal state can be easily detected by performing appropriate processing such as abnormal processing. Outflow of good products can be reliably prevented.

FIG. 7 shows steps (a) to (d) during arc welding.
It is a figure explaining the transfer phenomenon of the droplet in (h), a welding voltage waveform, and a welding current waveform.

[0024]

As described above, according to the method for judging the welding stability of the termination processing unit of the first aspect, the welding current and the welding voltage can be set at any one of (a) to (c) for a predetermined time. More than one item is calculated and compared with the corresponding reference value. When the difference between any one of the quantitative values and the reference value exceeds a preset allowable range, the welding phenomena of the termination processing part does not occur. There is an advantage that it can be determined in a real time whether it is stable or defective. Also, there is an effect that these data can be effectively used as an index for outputting a power supply control signal for an automatic recovery process when a welding abnormality occurs.

Further, according to the welding stability judging device of the present invention, the welding stability of the terminal processing part can be monitored in real time, accurately and quantitatively during welding, and the outflow of defective welding quality can be ensured. Has the advantage that it can be prevented.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an entire configuration of an embodiment of a termination processing section welding stability determination device of the present invention.

FIG. 2 is an analysis execution flowchart of the present invention.

FIG. 3 is a subroutine for performing an arc period welding current integral standard deviation calculation process;

FIG. 4 is a subroutine for performing a short-term welding current integral standard deviation calculation process.

FIG. 5 is a subroutine for performing an arc / short circuit time ratio standard deviation calculation process.

FIG. 6 is an explanatory diagram of a droplet transfer phenomenon, a welding voltage waveform, and a welding current waveform during arc welding.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 welding power supply 2 welding wire 4 contact tip 5 workpiece 6 shunt 7 welding current detection circuit 8 welding voltage detection circuit 9 A / D converter 10 CPU 16 display 17 calculation and output device

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Taro Kamiya 3-126-1, Kosakahonmachi, Toyota-shi, Aichi Prefecture Safinia MI602

Claims (2)

[Claims] In order to judge the arc welding stability of a consumable electrode type gas shielded arc welding in which welding is performed while alternately repeating a short circuit and an arc, a welding electrode (hereinafter referred to as a welding wire) and a material to be welded are determined. The analog output signal output by using the voltage detecting means for detecting the welding voltage of the welding wire and the current detecting means for detecting the welding current flowing between the welding wire and the material to be welded is converted into a digital signal at a predetermined sampling frequency and calculated. The following three items are input to the means and represent the degree of welding stability of the termination processing unit. (A) Standard deviation σ (∫I _An dt) of the welding current integral during the arc period for each cycle (b) One cycle Standard deviation σ (∫I _Sn dt) of the welding current integral value during the short-circuit period for each period (c) Arbitrary one or two items of the standard deviation σ (T _An / T _Sn ) of the arc / short-circuit time ratio for each cycle Calculate the above Compared with the reference value corresponding to each of them, when any one of the differences from the reference value exceeds a predetermined allowable range, it is determined that the welding of the termination processing unit is unstable or defective. A method for determining welding stability of an arc welding termination processing unit. 2. A consumable electrode type gas shielded arc welding end processing part arc welding stability judging device for welding while alternately repeating a short circuit and an arc, and detects a welding voltage between a welding wire and a material to be welded. Voltage detecting means, current detecting means for detecting a welding current flowing between a welding wire and a workpiece, an A / D converter for converting an analog output signal from both means into a digital signal, and a digital signal from the converter. (A) Standard deviation σ (∫I _An dt) of the welding current integral during the arc period for each cycle (b) Standard deviation σ (∫I _Sn dt) of the welding current integral during the short circuit period every cycle (C) A calculation means for calculating any one or more of the three items of the standard deviation σ (T _An / T _Sn ) of the arc / short-circuit time ratio for each cycle, and a calculation result from the calculation means. Preset criteria And a display for displaying the output of the comparator. The determination of the welding stability of the arc welding termination processing unit, comprising: a comparator for determining whether the difference from the reference value is within an allowable range. apparatus.