JP2000246441A - Remote monitoring device for welding state - Google Patents

Abstract

PROBLEM TO BE SOLVED: To clearly monitor an arc beam, molten pool, grooves and a torch by taking in a groove image at a first shutter speed when the arc is off, executing addition for each pixel of the two-dimensional array, showing it in a monitor and taking in the pixel at a second shutter speed for conversion processing at the time of welding. SOLUTION: Before the start of welding, a power source 5 for driving a light source is turned on by a signal from an external interface 21, and the shutter speed of the control circuit 6 of a two-dimensional light receiving means is set at a first speed, so that the image of a groove is taken in. This image is added successively for each pixel of the same coordinate of the two-dimensional array (X, Y) between plural sheets of image. The final image data thus added are data-converted and outputted to a monitor TV for display. During the welding, the power source 5 for driving the light source is turned off, and the shutter speed of the control circuit 6 of the two-dimensional light receiving means is set at a second speed, so that the image of a groove is taken in. This image data are converted and outputted to the monitor TV for display.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a welding condition monitoring apparatus for obtaining image information near an arc generating portion such as an arc light, a molten pool, a groove wall and a welding torch during welding.

[0002]

2. Description of the Related Art FIG. 6 shows a conventional welding status remote monitoring apparatus of this kind. In the figure, 1 is a light source such as a halogen lamp, 2 is a two-dimensional light receiving means such as an ITV,
3 is a band-pass filter for dimming arc light, 4
Is a motor. A plate 4 a on which the filter 3 is mounted is attached to the rotation shaft of the motor 4. The two-dimensional light receiving means 2 and the motor 4 are provided integrally. Reference numeral 5 denotes a drive power supply for the light source 1, and reference numeral 6 denotes a control circuit for the two-dimensional light receiving means 4, which outputs an analog video (image) signal to the outside. Reference numeral 7 denotes a monitor TV for displaying a video signal, 8 denotes a control circuit of the motor 4, 9 and 10 denote members to be welded, 11 denotes a welding groove (hereinafter, a groove including a welding bead is referred to as a groove), and 12 denotes welding. A torch, 12a is a welding wire, and 13 is an arc generating portion at the tip of the welding torch.

[0003] Before welding is started by such a monitoring device, the light source 1 is turned on, and the rotation of the motor 4 is controlled to move the bandpass filter 3 to a position where the bandpass filter 3 is removed from the front surface of the two-dimensional light receiving means 2. An image of the welding situation near the head is monitored by the monitor TV. During welding, the motor 4 is controlled to rotate to move the band-pass filter 3 to a position where the band-pass filter 3 is disposed in front of the two-dimensional light receiving means 2, and the two-dimensional light receiving means 2 obtained through the band-pass filter 3 is opened. An image near the head is monitored by the monitor TV.

[0004]

In a welding operation, if a traveling line of a traveling vehicle to which a welding torch is attached is shifted from a groove line to be welded, welding is performed at a position shifted from a position to be joined. Poor welding.
In addition, in the case of multi-pass multipass welding, since the number of passes of the weld bead is large, the welded work is deformed by thermal distortion or the like due to welding. In order to obtain a high quality weld bead, the position to be welded is accurately measured even when the setting of the welded work is out of alignment or when the work is thermally deformed by welding.
Welding must be performed by correctly imitating the welding torch.

In order to realize this, a method has been used in which a welding operator judges a welding condition while remotely monitoring a groove surface with a CCD camera or the like, and performs welding while manually correcting a welding electrode position. I have. For this purpose, it is necessary to clearly monitor the arc light during welding, the molten pool, the peripheral groove, and the welding torch.

The conventional apparatus shown in FIG. 6 monitors the welding condition before or during welding by opening and closing a band-pass filter by rotation of a motor. This method has a problem that the monitoring portion cannot be formed compactly because the motor, the plate, and the like are mounted around the two-dimensional light receiving means. In addition, there is a practical problem that a failure is likely to occur due to the presence of the rotating unit.

As a means for solving the above problem, a method of teaching all welding conditions and the like in advance by teaching without remotely monitoring the welding condition and executing welding is often adopted. On the other hand, it is necessary to accurately set the welding line path of the workpiece to be welded, or to accurately predict the thermal deformation due to welding in advance. There was a problem that there were restrictions.

An object of the present invention is to solve the above problem advantageously, and to provide a welding condition monitoring device capable of clearly monitoring an arc light during welding, a molten pool, a peripheral groove portion and a welding torch. is there.

[0009]

In order to achieve the above object, a light emitting means for irradiating an arc generating part and its vicinity, a two-dimensional light receiving means such as an ITV equipped with a filter and photographing a welding part, and a two-dimensional light receiving means. An apparatus for monitoring a welding situation by displaying an image output from a light receiving means on a monitor TV, comprising: an image memory comprising a plurality of sheets for capturing and storing an image output from the two-dimensional light receiving means; An inter-image arithmetic processing unit that performs addition and subtraction between memories,
When an arc is OFF, an image processing device including an image data conversion unit for performing density conversion and the like is used. The groove images are sequentially captured at the first shutter speed t1, and the images captured by the image processing device are exchanged between a plurality of images. The addition for each pixel of the same coordinates of the dimensional array (X, Y) is sequentially executed and output and displayed on the monitor TV. At the time of welding, an image is taken in at the second shutter speed t2, and image data is obtained according to the purpose of monitoring the welding situation. The converted image is output and displayed on the monitor TV.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a schematic configuration diagram showing one embodiment of a welding status remote monitoring apparatus according to the present invention. In the figure, FIG.
The same parts are indicated by the same symbols. Reference numeral 14 denotes an image processing apparatus comprising the following parts. 15 is an image input unit for A / D converting an analog image signal output from the light receiving means control circuit 6 into a digital amount and outputting multi-valued image data;
Reference numeral 16 denotes an image memory for storing image data, which is constituted by a multi-valued image memory composed of a plurality of sheets or a binary image memory.

Reference numeral 17 denotes an inter-image calculation processing unit for calculating addition or subtraction between image memories from image data stored in the image memory 16, and reference numeral 18 denotes smoothing (noise removal) and differentiation (edge processing) using the image data. A filtering unit 19 for performing a filtering process such as emphasis), an image data conversion unit 19 for performing a density conversion or the like for enhancing contrast, an image display unit 20 for displaying an input image, an image processing result, and the like, 21
Denotes an interface with an external device (hereinafter, abbreviated as an external I / F). Reference numeral 22 denotes a main control unit that controls the above units in a comprehensive manner. Reference numeral 23 denotes a remote control box, which is used by an operator to externally teach image processing contents and procedures, and the image processing apparatus 1.
4 for operating image input, execution of image processing, and the like.

Next, the operation of the remote monitoring device of the present invention and the method of monitoring the welding status will be schematically described. The transmission wavelength of the bandpass filter 3 is not particularly limited, but is preferably a wavelength near the peak wavelength in the spectral sensitivity of the two-dimensional light receiving means used. First, conditions for setting the aperture of the two-dimensional light receiving means will be described. When welding is not performed and the shutter speed of the two-dimensional light receiving unit is set to the minimum (the shutter speed at this time is referred to as a first shutter speed t1) and the irradiation light amount of the light source 1 is increased, the observation unit The aperture of the two-dimensional light receiving means is set as small as possible until the brightness of the image is slightly observed.

During welding, since the arc light is strong, the shutter speed is increased to set optimum conditions (the shutter speed at this time is set to a second shutter speed t2), and observation is performed. Since the minimum shutter speed is set to t1 and the two-dimensional light receiving means is reduced to the maximum, it is possible to set a flexible setting even for strong arc light during welding.

Before the start of welding, that is, when the arc is OFF,
First, the lamp driving power supply 5 is supplied by a signal from the external I / F 21.
Is turned on to turn on the light, and then the shutter speed of the light receiving means control circuit 6 is set to t1 by a signal from the external I / F 21 to capture an image of the groove. As described above, an image observed at this shutter speed is observed as a dark image.

Therefore, the image fetched by the image processing apparatus is sequentially added to a plurality of images for each pixel of the same coordinates in the two-dimensional array (X, Y). The finally added image data is subjected to data conversion so that the gradation does not exceed, for example, 256 gradations, transferred to the image display unit, and output and displayed on the monitor TV. Even for a one-frame image, even a dark image can acquire a sufficiently bright monitoring image by adding and accumulating a plurality of image data.

On the other hand, during welding, the lamp drive power supply 5 is first supplied by a signal from the external I / F 21 immediately before the start of welding.
Is turned off to turn off the light, and then the shutter speed of the light receiving means control circuit 6 is set to t2 based on a signal from the external I / F 21 to capture an image of the groove. In this case, arc O
An image is output and displayed without adding a plurality of image data at the time of FF. However, the image data is converted according to the purpose of monitoring the welding status, and the image is output and displayed. Hereinafter, the contents of the conversion processing of image data during welding according to the present invention will be described.

FIG. 2 schematically shows an example of an acquired image at the time of welding stored in the image memory 16. In the figure, black and white are reversed, that is, a bright (high luminance) portion is expressed as black, and a dark (low luminance) portion is expressed as white, contrary to a normal image. 12 is a welding torch, 1a is an image of a welding wire. 23 is a molten pool image, 24 is an arc light image, and 25 is a welding line.

Reference numerals 9a, 9b, and 9c denote reflection images of a groove slope, a groove shoulder, and a groove surface of the member 9 to be welded, respectively. Similarly, 10a, 10b, and 10c are reflection images of the groove slope, the groove shoulder, and the groove surface of the member 10 to be welded, respectively. Regarding the brightness (luminance) relative value of the image of each part, the normal arc light 24 is the brightest, and then the molten pool 23, the groove slopes 9a and 10a near the molten pool and the welding wire 1a are imaged brightly. In the welding torch, only the end face of the tip is slightly brightly imaged. If the weld bead is at the bottom of the groove, no reflection image of the groove surface will appear.

FIG. 3 schematically shows the luminance distribution of each pixel on the AA horizontal line in FIG. In the figure,
Xs is the left edge of the screen, X1 is the left groove shoulder position, X2 is the left groove slope and the left boundary position of the molten pool, X3 is the boundary position between the molten pool and the left arc image, and X4 is the boundary between the right arc image and the molten pool. The position, X5 is the boundary position between the right molten pool and the right bevel slope, X6 is the right bevel shoulder position, and Xe is the right edge of the screen.

The tendency of the brightness of the image on the left side from the center Xc of the molten pool is as follows. The X (horizontal) coordinate value is in the range from XS to X1, that is, the brightness on the groove surface is I9c, which is the darkest. The brightness corresponding to the groove slope from X1 to X2 gradually increases as approaching I9c to I9b and the molten pool. The brightness sharply increases from I9b to I23 at the left boundary point between the left groove slope of X2 and the molten pool, and the brightness rapidly increases from I23 to I24 at the boundary point between the molten pool and the left arc image of X3. The tendency of the brightness of the image on the left side from the center Xc of the molten pool is similar, although the brightness level slightly changes.

Next, a method of converting image data during welding in the welding condition monitoring apparatus of the present invention will be described with reference to FIG. FIG. 4 shows a method of converting the input image data. The horizontal axis represents the luminance (Im) of each pixel of the input image, and the vertical axis represents the luminance (Im) of each pixel when output and displayed on a monitor or the like.
c). The straight line L1 is a case where the luminance Ic is determined in a one-to-one (linear) relationship with the luminance Im of the input data. On the other hand, when the straight line L2 satisfies (0 ≦ Im ≦ Im2) with respect to the luminance Im of the input data, the gradation conversion represented by the equation (1) is performed to determine the luminance Ic.

[0023]

(Equation 1)

In addition, for the luminance Im of the input data, (I
When m2 <Im ≦ Immax), the gradation conversion shown in the equation (2) is performed to determine the luminance Ic.

[0025]

(Equation 2)

Similarly, a straight line L2 represents the luminance Im of the input data.
On the other hand, when (0 ≦ Im ≦ Im3), the gradation conversion represented by the equation (3) is performed to determine the luminance Ic.

[0027]

(Equation 3)

Also, for the luminance Im of the input data, (I
When m3 <Im.ltoreq.Immax), the gradation conversion shown in the equation (4) is performed to determine the luminance Ic.

[0029]

(Equation 4)

The image data conversion of the straight line L2 is a method of lowering the contrast with respect to the luminance Im lower than Im2 and increasing the contrast with respect to the luminance Im higher than Im2 at the boundary of the brightness of Im2.

The image data conversion of the straight line L3 is a method of increasing the contrast with respect to the luminance Im lower than Im3 and decreasing the contrast with respect to the luminance Im which is higher than Im2 at the boundary of the brightness of Im3. This data conversion method is shown in FIG.
In this case, the contrast of the brightness of the arc light 24, the molten pool 23, and the brightness of the groove slope near the molten pool is increased.

FIG. 5 qualitatively shows a luminance distribution when gradation conversion by data conversion of L2 and L3 is performed on the image showing the luminance distribution of the horizontal line in FIG. From FIG. 5, the data conversion method of L2 increases the contrast between the arc light 24 and the molten pool 23 and reduces the brightness of the groove slopes 9a and 10a in terms of the symbols in FIG.
This case is suitable for processing the image of the arc light or the molten pool and detecting the shape feature amount thereof for the purpose of controlling the groove following control or the welding condition control.

The data conversion method of L3 increases the brightness of the arc light 24 and the molten pool 23 and also increases the brightness of the groove slopes 9a and 10a.

Which type of image data conversion method to use in the present invention is to be set in advance in the main control unit 22 in the image processing apparatus by the remote control BOX 21. The data conversion of the image is performed by the data conversion unit 19. The image after the data conversion may be subjected to filtering processing such as smoothing (removal of noise) and differentiation processing (edge enhancement) of the image data via the filtering processing unit 18 to be output and displayed.

[0035]

As described above, the welding condition remote monitoring device of the present invention sets the shutter speed of the two-dimensional light receiving means to the first condition t1 before welding starts, that is, when the arc is turned off.
, The groove image is fetched, and the image fetched by the image processing device is sequentially added to the plurality of images for each pixel of the same coordinates (X, Y) of the two-dimensional array (X, Y), The image data is converted so that the tone does not exceed, for example, 256 gradations, and output and displayed on the monitor TV. Further, during welding, the shutter speed of the two-dimensional light receiving means is set to the second condition t2, an image is captured, image data is converted according to the purpose of monitoring the welding status, and the image is output and displayed.

According to the above monitoring method, it is possible to provide a good monitor image required for remote welding work with a compact configuration that does not use a mechanism for opening and closing the band-pass filter by a motor or the like. In addition, since there is no opening / closing operation mechanism for the filter, that is, no operating part, there is an effect that the number of failures is small and the reliability is high.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a welding status remote monitoring device according to the present invention.

FIG. 2 is a cross-sectional view showing an example of an acquired image during welding according to the present invention.

FIG. 3 is a characteristic diagram of a luminance distribution of each pixel on a horizontal line according to the present invention.

FIG. 4 is a characteristic diagram showing a method of converting image data during welding in the welding status remote monitoring device of the present invention.

FIG. 5 is a luminance distribution diagram when gradation conversion is performed in the welding status remote monitoring device of the present invention.

FIG. 6 is a schematic configuration diagram showing a conventional welding status remote monitoring device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Light source, such as a halogen lamp, 2 ... 2D light receiving means, 3
... Band pass filter, 4 ... Motor, 4a ... Plate,
5 ... light source drive power supply, 6 ... two-dimensional light receiving means control circuit, 7 ...
Monitor TV, 8 ... Motor control circuit, 9, 10 ... Member to be welded, 11 ... Welding groove, 12 ... Welding torch, 12a ... Welding wire, 13 ... Arc generator, 14 ... Image processing device, 1
5 ... Image input unit, 16 ... Image memory, 17 ... Inter-image calculation unit, 18 ... Filtering processing unit, 19 ... Image data conversion unit, 20 ... Image display unit, 21 ... External device interface, 22 ... Main control unit, 23 ... Remote control box.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Mitsuaki Haneda 502 Kandachi-cho, Tsuchiura-shi, Ibaraki Inside Machinery Research Laboratory, Hitachi, Ltd. (72) Inventor Takeshi Wada 3-1-1, Sachicho, Hitachi-shi, Ibaraki Stock Hitachi, Ltd. Hitachi Plant (72) Inventor Yasukata Oi 3-1-1, Sachimachi, Hitachi, Ibaraki Prefecture F-term in Hitachi, Ltd. Hitachi Plant 5B057 AA19 BA11 CA12 CA16 CB12 CB16 CE03 CE05 CE06 CE08 CE11 CH01 CH11 5C022 AA01 AB12 AB15 AB17 AC01 AC31 AC42 AC54 AC55 AC56 AC69 AC74 5C054 AA01 AA05 CA04 CB03 CC05 CH02 EA01 EA05 ED02 ED12 ED13 ED17 EJ04 EJ05 FC03 FC12 HA03

Claims (1)

[Claims] A two-dimensional light receiving means such as an ITV equipped with a filter and illuminating a welded part, and an image output from the two-dimensional light receiving means is displayed on a monitor TV. In the apparatus for monitoring the welding condition, an image memory composed of a plurality of sheets for capturing and storing the image output from the two-dimensional light receiving means, and an image for performing addition between the image memories using the stored image data An image processing apparatus including an interval calculation processing unit and an image data conversion unit for performing density conversion and the like is used.
The groove images are sequentially captured at the shutter speed t1, the addition of the images captured by the image processing device is sequentially performed between a plurality of images, and the image is output and displayed on the monitor TV. At the time of welding, the images are captured at the second shutter speed t2. A welding condition remote monitoring device characterized in that an image obtained by converting image data according to the purpose of capturing and monitoring the welding condition is output and displayed on a monitor TV.