JP3046372B2 - Image analysis device for arc welding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image analysis apparatus for arc welding, and more particularly to an apparatus for extracting and analyzing a necessary portion from a video signal obtained by photographing the vicinity of an arc during welding.

[0002]

2. Description of the Related Art Welding arcs are always used except when the arc length is intentionally changed, such as when pulse welding is performed, or when the same change is repeated stably such as droplet transfer welding with a consumable electrode. It is desirable to be stable from the viewpoint of welding workability such as welding defects or spatters and safety, and conventionally, these evaluations have been performed qualitatively in a human sense or in a very short time.

[0003] However, it is clear that evaluation based on human sensation lacks reliability in an evaluation in a very short time because evaluation criteria vary depending on individuals and evaluation standards vary.

In addition, when measuring, for example, the arc length and the size of a molten pool just under or near the arc during welding, it is difficult to apply a scale, and conventionally, after extinguishing the welding arc, After the temperature was sufficiently lowered, the distance between the base metal and the tip of the wire was measured, and this was used as the arc length.

However, these measuring methods cannot not only perform real-time measurement, but also cannot extinguish the arc during welding due to the occurrence of welding defects. Even if it is an experimental test piece, the inertia of the motor after the supply of the consumable electrode is stopped, or the reactance existing inside the welding power supply after the welding power supply is stopped or the floating reactance due to wiring, etc. after the welding power supply is stopped. Since it is difficult to extinguish the arc immediately and it may be more or less than the actual arc length, or even if the molten pool is completely solidified, the boundary of the molten pool is not clear after the molten metal has completely solidified. It is very difficult to measure the value.

Therefore, in the conventional method for evaluating the welding arc stability, it has been general to quantitatively evaluate the welding current, the arc voltage, the consumption rate of the electrode and the like by substituting the level with a meter.

[0007]

However, although these quantities are items related to the arc, they are not arcs themselves, so that reliability remains a question.

Conventionally, a general image analysis apparatus uses
Since it takes a lot of time to process the screen, once the image is fetched into the storage device and the process is performed in a fixed state as a still image, the following different phenomena already occur within the time to execute the process, and it is very continuous It was difficult to capture the phenomena, and it was difficult to perform accurate analysis.

SUMMARY OF THE INVENTION It is an object of the present invention to easily obtain real-time accurate information on control of an arc state or welding.

The image analysis apparatus for arc welding according to the present invention converts a video signal indicating a state near an arc during welding at a set level.
Binarization processing means (42) for sequentially binarizing the image signal ;
A vertical counter (21,
24), means for specifying the vertical area (23, 26) and the vertical
Counter (21, 24) count data in the vertical direction
Indicates whether it is within the area specified by the specifying means (23, 26)
Vertical signal area including comparison means (22, 25) for generating
A Designating circuit (2) ; horizontal counters (31, 34), horizontal area
Specifying means (33, 36) and the counter of the horizontal counter (31, 34)
Data is provided by the horizontal area designating means (33, 36).
Comparison to generate a signal indicating whether the area is within the specified area
Horizontal signal area designation circuit including means (32, 35) (3); the vertical
Direct signal area designating circuit (2) and horizontal signal area designating circuit
Based on a signal indicating whether or not the area where the road (3) occurs,
The video signal, the vertical area designation means (23, 26)
And the horizontal area specification means (33, 36).
AND operator that generates a signal indicating whether or not it is within the specified two-dimensional area
Stage (7a) ; a signal indicating that the logical product means (7a) represents the inside of the two-dimensional area
The binarization processing means (42) performs binarization when
Means for extracting the extracted signal (11, 7c) ;
Combining circuit for sequentially combining the binarized signal issued superimposed with the video signal (8); said logical product means (7a) is a two-dimensional area
The binarization processing means while generating a signal representing
(42) measures the length of one of the high and low levels of the binarized signal.
Measurement counter (5) to measure ; count of the measurement counter (5)
De - latching means for holding the data (Lt); and, wherein
In synchronization with the switching signal of the scanning line of the video signal,
The count data of the measurement counter (5) to the switching means (Lt).
Means (10a, 10a)
b) ;

Symbols in parentheses indicate corresponding elements or items in the embodiment shown in the drawings and described later.

[0012]

According to this, the vertical region of the video signal indicating the state near the arc during welding obtained by using the imaging device is set to the vertical direction.
The signal area designating circuit (2) converts the horizontal area to the horizontal signal area.
The designation circuit (3) designates the logical product means (7a) and the extraction means (11,7
c) and the two-dimensional area specified by the synthesis circuit (8)
Of the binarized video signal is extracted and combined with the video signal.
Is done. When this synthesized signal is displayed on the display,
The two-dimensional area is confirmed on the image showing the state near the arc.
It can be recognized. In addition, the measurement counter (5)
The binarization processing means (42) within the selected two-dimensional area
Since the length of one of the high and low levels of the measured signal is measured,
The two-dimensional area is defined as an area centered on the arc being welded.
Measuring the level corresponding to the arc light of the binary signal
This allows safe and real-time measurements at various locations under the actual arc without extinguishing the arc.
Finally , the arc length is obtained.

As described above, the composite signal is displayed on the display.
When displayed, the secondary
In addition to confirming the original area, that is, the measurement location ,
The measured length value is latched by the latch means (Lt) for each scanning line.
So, for example, extract the latch data and display it on the display.
Display or the latch means (Lt)
D / A conversion of data and graph recording with analog recorder
By doing so, the measurer can visually confirm the measurement according to the change of the arc itself during welding in real time, and at the same time, can record a specific numerical value at that time.

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

[0015]

FIG. 1 shows an electric system according to an embodiment of the present invention. A circuit for inputting a video signal obtained by imaging the vicinity of a welding arc and separating a vertical synchronizing signal and a horizontal synchronizing signal of the signal, a vertical signal area specifying circuit 2 for specifying an area where information desired by a measurer appears, and a horizontal signal Area designation circuit 3, video signal binarization circuit 4 for facilitating measurement of video signal 4, measurement counter circuit 5 for measuring length or size 5, D / A converter 6 for converting the measurement value to analog value 6, It is composed of an image signal synthesizing circuit 8 for outputting a signal for displaying the measurement location on the original screen, a transmitter (4 MHz) 9 for synchronizing all of these times, and the like. However, if the number of measurement points is different and a plurality of measurement points are provided, the number of necessary circuits may be increased by the number of the measurement points.

The input video signal is a general NTS
C (short for National Television System Committee) Any signal that conforms to the signal may be used as a video signal from a general television camera, or the signal may be recorded or played back from what has been written to the storage device by any method. The video signal may be a signal from a video tape recorder, for example, a video signal conforming to the NTSC standard.

Here, an image displayed on a television screen will be briefly described.

As shown in FIG. 2, an image displayed on a television screen or a cathode ray tube has one screen composed of 525 scanning lines, and among them, odd-numbered and even-numbered operation screens are divided by 1 /. It is projected every 60 seconds, and one screen is composed of 1/30 seconds. Therefore, a total of 30 screen images are displayed in one second, and are seen as continuous movements by the human eye without interruption in time.

FIGS. 3 and 4 show these video signals.
As shown in (1), a horizontal synchronizing signal is included as a signal for switching a scanning line scanned in a substantially horizontal direction on a screen, and a vertical synchronizing signal is included as a screen switching signal transmitted every 1/60 second.

Referring back to FIG. Since the video signal contains a huge amount of information for each scanning line, the vertical counter A21 and the vertical counter B22, which constitute the vertical signal area designating circuit 2, and the horizontal signal area designating circuit 3 constitute the vertical signal area designating circuit 2 in order to narrow down the area required for measurement. Are provided, the horizontal and vertical areas are designated by providing a horizontal counter A31 and a horizontal counter B32. Of course, there is no problem even if the designated area is filled with the screen. When a video signal is input here,
A part of the signal is separated by the horizontal and vertical synchronization signal separation circuit 1 into only respective synchronization signal components. The separated signal is input to the vertical counter A21, and the vertical counter A21 starts counting the number of pulses (horizontal synchronization signal) (the number of measured pulses is cleared every time the vertical synchronization signal is input). The number of pulses is counted by the vertical counter A21, which is set in advance by using the digital switch A23 to set the number of the vertical scanning line near the target to be measured as an approximate area and set the number by the digital switch A23. When the calculated values become the same, the digital comparator A22 sends a signal for starting the operation of the vertical counter B24. The vertical counter B24 determines the required vertical area of the image.
26.

Similarly, the area of the horizontal synchronizing signal is roughly set by the digital switch C33 and the digital switch D36 according to the required position from the end of the screen (the number of pulses output from the transmitter 9 is counted). The number of pulses is cleared each time the horizontal synchronizing signal falls). The horizontal counter A31 and the horizontal counter B only when the vertical counter comes within a required vertical area.
34 is operated, and when the value to start counting the time based on the horizontal synchronizing signal becomes equal to the preset value, the horizontal counter B34 presets the horizontal direction. A signal for capturing a video signal corresponding to the range of the area is output from the digital comparator D35. A signal whose area is designated by the digital comparators A22 and B25 in the vertical direction and a signal whose area is designated by the digital comparators C32 and D35 in the horizontal direction are input to the AND circuit A7a, and these signals are all turned ON. Only when this happens, a signal is output from the AND circuit A7a.

On the other hand, a part of the input video signal constitutes a video signal binarization circuit 4 in accordance with the brightness of the video projected on the screen at a measurement location in order to make it easy to identify the signal to be measured. An analog comparator circuit 42 is provided at the threshold value of the brightness desired by the operator by the binarization level setting volume 41.
, The signal is converted into a binary signal. For example, when it is desired to measure the arc length, the threshold value in the binarization level setting circuit 23 may be selected so that the brightness from the tip of the electrode to the surface of the base material becomes bright.

A part of the signal binarized in this way is the signal output from the AND circuit A7a and the signal from the transmitter 9
The output reference clock signal is input to the AND circuit B7b, and the output signal is input to the measurement counter circuit 5 only when all these signals are turned ON.

Therefore, the measurement counter circuit 5 measures the input signal based on the reference clock signal output from the transmitter 9. Note that a signal from the detector 10b that detects the fall of the horizontal synchronization signal is input to the measurement counter circuit 5, and the number of clock pulses measured by the counter is cleared each time the fall signal is input. Further, since the signal from the detector 10a for detecting the rise of the horizontal synchronizing signal is input to the latch circuit provided in the measurement counter circuit 5, the number of clock pulses counted by the measurement counter circuit 5 every time the rising signal is input is calculated. Latched.

As a result, the pulse width (distance) of the output signal level binarized in the designated area can be known. Since the measured output signal from the measurement counter circuit 5 is a digital signal, it is written and stored as data by a computer or the like in a storage medium such as a magnetic disk or a solid-state storage element.

The digital signal output from the measurement counter circuit 5 is converted by the D / A converter 6 into an analog signal. Since the analog signal is input to a recorder 12 such as a pen recorder capable of recording a change with time, its output is observed in real time.

The digital signal output from the measurement counter circuit 5 can be used to control the feed rate of the electrode as a control of the arc phenomenon, and further, to a feedback control signal such as welding current control and arc voltage control. .

A signal taken out from the intermediate point between the AND circuit B7b and the measurement counter circuit 5 is sent to the shift register 13 of the microcomputer device for performing data processing using the microcomputer, and to the signal from the transmitter 9 The signal from the pulse signal falling detector 10b was also input.

On the other hand, a part of the signal binarized by the analog comparator circuit 42 is inverted in the nature of the signal in the NOT circuit 11 and is input to one of the following AND circuits C7c, and the other is designated as the area designated above. A part of the signal (output signal from the AND circuit A7a) is added and subjected to AND processing. The signal output from the AND circuit C7c is added to the video signal from the beginning by the video signal synthesizing circuit 8 in order to clarify the measurement location, and becomes an image in which the measurement location can be confirmed on the screen. Therefore, the measurer can visually confirm the measurement according to the change in real time, and can also record the specific numerical value at that time.

If the statistical processing of the recording is performed by a computer or the like, for example, the number of times a short circuit occurs between the electrode and the base material during welding or the number of droplets moving away from the tip of the electrode can be simultaneously determined. Measurement processing can be performed, and measurement and analysis with a wide range of application can be performed.

Here, a case is shown in which a video tape reproduction signal when gas shield welding using a solid wire is performed is input as the video input signal shown in FIG.

The electrode wires used at this time were Si-M
Using n-type wire diameter of 1.2mmφ, welding current is 280A
The shielding gas used was Ar-CO ₂ (CO ₂ 20%), and the welding time was 2 minutes.

As shown in FIG. 5, the measurement location was an arc length, a horizontal designated area from the vicinity of the electrode tip to the base metal surface, and a vertical designated area was designated as an area sufficiently including the arc frame. Note that a pen-written recorder was used as the recorder 12 shown in FIG.

FIG. 6 shows a screen in the vicinity of the arc binarized by the brightness of the arc frame in the designated area. FIG. 7 shows the arc length at the time of scanning the line A (arc length) shown in FIG. The video signals are shown in (a), (b) and (c), respectively.

As a result, the instantaneous change in the arc length appeared on the pen writing recorder 12 without delay, and the data processed by the microcomputer was displayed on the television picture screen without any delay. At this time, the average arc length was 2.86 mm, and the maximum arc length was 4.35.
mm, the minimum length was 1.96 mm, and the number of short circuits, that is, the number of times when the arc length was 0 mm, was not found. Also, no arc break was observed.

[0036]

According to the present invention, accurate information such as the length of an arc can be obtained safely and in real time without extinguishing the arc in any measurement at various points under the actual arc. In addition, this makes it possible to measure and analyze the phenomena themselves appearing on the television image screen. Further, using the results, a command is given as a feedback signal to a welding power source or an electrode supply device to input welding heat, aim at the electrode, and swing the electrode. Welding quality such as motion can be controlled.

[0037] Also, since the signal indicating the measurement points to be overlaid with the video signal, the measurement position can be confirmed on the screen based on the video signal from the beginning. Therefore, the measurer can visually confirm the measurement corresponding to the change of the arc itself during welding in real time, and can record a specific numerical value at that time.

Furthermore, attention is paid to an image from which a large amount of information can be obtained in real time as information, and some information is extracted for each purpose from video signals constituting the image, and the extracted signals are processed, so that each image is displayed on a video screen. Multiple changes in the welding arc phenomenon corresponding to the changes can be captured.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an electric system according to an embodiment of the present invention.

FIG. 2 is a plan view showing the outline of the principle of television video.

3A and 3B are time charts showing a relationship between a television video signal and a synchronization signal, wherein FIG. 3A is a time chart showing a video signal, FIG. 3B is a time chart showing a horizontal synchronization signal, and FIG. 6 is a time chart illustrating a composite video signal.

FIG. 4 is a time chart illustrating a relationship among a horizontal synchronization signal, a vertical synchronization signal, and a composite signal.

FIG. 5 is a plan view showing an image in which an area near an arc during welding is specified.

6 is a plan view showing a screen near an arc after a binarization process is performed on the designated area shown in FIG. 5 with the brightness of the arc frame.

FIG. 7 is a time chart showing an example of a video signal with respect to a change in arc length when scanning the line A shown in FIG. 6;

[Explanation of symbols]

1: horizontal, vertical sync separation circuits 2: vertical signal area specified circuits 3: horizontal signal area specified circuits 4: video signal 2 Nekakai
Road 5: Measurement counter circuits 6: D / A converter 7a: logical product circuit A 7b: AND circuit B 7c: AND circuit C 8: video signal combining circuits 9: transmitter 10a: pulse signal rise detector 10b : pulse signal falling detector 11: denial circuitry 12: recorder 13: shift register 21: the vertical counter A 22: digital comparator A 23: digital switch A 24: vertical counter B 25: digital comparator B 26: digital switch B 31: horizontal counter A 32: digital comparator C 33: digital switch C 34: horizontal counter B 35: digital comparator D 36: digital switch D 41: 2 binarization level setting volume 42: analog comparator Lt: latch circuits

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yuji Suzuki 7-6-1, Higashi Narashino, Narashino City, Chiba Prefecture Nippon Steel Welding Industry Co., Ltd. (72) Inventor Osamu Maruyama Higashi Narashino, Narashino City, Chiba Prefecture 7-6-1, Nippon Steel Welding Industry Co., Ltd. Laboratory (56) References JP-A-61-17366 (JP, A) JP-A-1-40176 (JP, A) JP-A-61-116606 (JP) , A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G06T 1/00 G06T ⁷ /00-7/60 B23K 9/095

Claims (1)

(57) [Claims] 1. A binarization processing means for sequentially binarizing a video signal indicating a state in the vicinity of an arc during welding at a set level; a vertical line counting a scanning line switching signal of the video signal.
Direct counter, vertical area designating means and the vertical
The count data of the counter is the area specifying means in the vertical direction.
Generates a signal indicating whether or not it is within the area specified by
Vertical signal area designating circuit including comparing means ; horizontal counter, horizontal area designating means, and the horizontal
The count data of the counter is the horizontal area designating method.
Generates a signal indicating whether it is within the area specified by the step
Horizontal signal area designating circuit including comparing means ; vertical signal area designating circuit and horizontal signal area designating circuit
Based on a signal indicating whether the circuit
The video signal is output from the vertical area designating means and the horizontal direction.
Within the two-dimensional area specified by the direction area specifying means
AND means for generating a signal indicating no ; the AND means generating a signal indicating the inside of the two-dimensional area
Extracting the binarized signal when the binarization processing means
That means; 該摘out combining circuit means for sequentially combining overlapping with the video signal obtained by binarizing the signal excised; by the logical product means to generate a signal representing a two-dimensional area
While the signal is binarized by the binarization processing means,
A measurement counter for measuring one of the low-level lengths ; a latch for holding count data of the measurement counter ;
And means for synchronizing with the switching signal of the scanning line of the video signal.
The count data of the measurement counter is latched by the latch means.
Means for initializing the measurement counter ; and an image analysis apparatus for arc welding, comprising: