JP2014210273A - Welding method and welding apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve welding quality by exerting a control to make correction according to a change in a plate gap value or a deviation of a welding position.SOLUTION: An image of a welded portion WZ is picked up, a bead width value is detected based on the picked-up welded portion image, a plate gap value is obtained from the bead width value, and welding is carried out while exerting a control to correct welding conditions or mainly a welding speed based on the plate gap value. Furthermore, an optical image shape formed by an area in the welded portion image having a brightness value equal to or higher than a certain value is detected, a welding position X is detected from the optical image shape, and welding is carried out while exerting a control to correct the welding position X by comparing the welding position X with a set position.

Description

  The present invention relates to a welding method and a welding apparatus suitable for improving welding quality in arc welding or the like.

Conventionally, there has been a welding method described in Patent Document 1 as this type of technology.
This is because, in the lap welding of thin steel plates, laser output is performed so that the weld bead width satisfies the condition expressed by the following formula (1) when performing gas metal arc welding after irradiating the YAG laser to the planned welding location. In this welding method, the arc current and the welding speed (welding conditions) are adjusted to improve the welding quality.
W> TS × t / (1.9 × Hv) (1)
However, W (mm): Weld bead width (bead width between two plates), Hv: Vickers hardness of the weld metal, t (mm): Plate thickness (Ts × of two thin steel plates to be welded together) TS (MPa): Tensile strength (the side with the smaller TS × t value of the two thin steel plates to be lap welded).

JP 2002-144063 A

In the above prior art, the bead width can be controlled by the above equation (1), and it is expected to improve the welding quality.
By the way, when the plates are welded to each other as described above, they are overlapped so as not to generate a gap between the plates. This is because when the gap is generated, the weld quality is deteriorated particularly when the value of the gap (the gap value) is changed. However, in practice, a gap may occur due to a lack of pressure when the plates are brought together.
In the above-described prior art, improvement in welding quality by control (correction control) that corrects according to such a change in the sheet gap value or deviation (target deviation) of the welding position is not taken into consideration. Improvement in welding quality cannot be expected.

  The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a welding method and a welding apparatus that can improve welding quality by control that is corrected in accordance with a change in sheet gap value or a deviation in welding position. And

The said subject is solved by making the welding method and a welding apparatus the structure of each following aspect.
As with the claims, each aspect is divided into sections, each section is numbered, and is described in a form that cites the numbers of other sections as necessary. This is merely for the purpose of facilitating the understanding of the present invention, and the technical features described in this specification and combinations thereof should not be construed as being limited to those described in the following sections. . In addition, when a plurality of items are described in one section, it is not always necessary to employ the plurality of items together, and it is also possible to take out only a part of the items and employ them.

  Of the following items, (1) is in claim 1, (2) is in claim 2, (3) is in claim 3, (4) is in claim 4, (5) The term corresponds to claim 5, the (6) term corresponds to claim 6, and the (7) term corresponds to claim 7.

(1) A welding method for welding a plate and a plate, taking an image of a welded portion, detecting a bead width value based on the taken welded portion image, and detecting a bead width value between the plate and the plate to be welded from the detected bead width value. A welding method characterized by obtaining a value of a gap and performing welding while controlling to correct a welding condition based on the obtained value of the gap.
(2) The welding method according to (1), wherein the welding condition is a welding speed, and welding is performed while controlling to correct the welding speed based on the value of the plate gap.
(3) A welding method for welding plates to each other, wherein an image of a welded portion is photographed, and a light image shape formed by a region having a luminance value equal to or greater than a certain value in the photographed welded portion image is detected and detected. A welding method comprising: detecting an actual welding position from an optical image shape; and performing welding while performing control to correct the welding position by comparing the detected welding position with a set position.
(4) Arc welding is used for welding, The welding method as described in any one of the items (1) to (3).
(5) The welding method according to (4), wherein the light image shape is an arc light image shape.
(6) A welding device for welding a plate to a plate by controlling a welding robot with a robot control device, and a bead width value based on an image of the welded portion and an image of the welded portion from the imaged means. Detecting a gap value between the plates to be welded from the detected bead width value, and a control signal for correcting welding conditions based on the obtained gap value and / or in the welded portion image Image processing means for detecting an actual welding position from the optical image shape of the image and comparing the detected welding position with a set position to output a control signal for correcting the welding position. A welding apparatus, wherein the robot controller receives a signal and performs welding while controlling the arc welding robot.
(7) The welding condition is a welding speed, and the image processing means outputs a control signal for correcting the welding speed based on the value of the plate gap. Welding equipment.

According to the invention described in item (1), it is possible to provide a welding method capable of improving the welding quality by control for correction according to a change in the value of the gap.
According to the invention described in the item (2), it is possible to provide a welding method capable of improving the welding quality by the control for correcting the welding speed.
According to the invention described in the item (3), it is possible to provide a welding method that can improve the welding quality by the control that is corrected according to the deviation of the welding position.
According to the invention described in item (4), the effect of the invention described in any one of items (1) to (3) can be obtained in arc welding.
According to the invention described in item (5), the effect of the invention described in item (4) can be obtained in arc welding in which the actual welding position is detected from the arc light image shape.
According to the invention as described in the item (6), it is possible to provide a welding apparatus capable of improving the welding quality by the control that is corrected according to the change in the value of the gap or the deviation of the welding position.
According to the invention described in the item (7), it is possible to provide a welding apparatus capable of improving the welding quality by the control for correcting the welding speed.

It is a figure which shows an example of a welding part image. It is explanatory drawing of the clearance value detection in the method of this invention. It is explanatory drawing of the welding position detection in this invention method. It is a graph which shows an example of the relationship between the bead width value and board gap value which are shown in FIG. It is a block diagram showing one embodiment of a welding device to which the method of the present invention was applied.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same reference numerals indicate the same or corresponding parts.
First, the background to the present invention will be described.
In arc welding or the like, if the width of the weld bead (bead width) can be controlled, the welding quality can be improved. However, the improvement of the welding quality is not limited to the control of the bead width.
For example, the welding quality can be improved by controlling the welding conditions and the welding position in accordance with the change in the value of the gap (the gap value) and the deviation of the welding position. This is because if the gap value or welding position deviation is large, the welding quality may be deteriorated.
However, it is necessary to detect the gap value and the welding position easily and quickly in order to correct the welding conditions and the welding position according to changes in the gap value and the deviation of the welding position. However, a method suitable for this has not been found in the past.

Therefore, the present inventors have obtained the following findings (1) and (2) as a result of intensive experiments and examinations.
In addition, the weld part image referred in the following description is as follows.
A welded part image 1 illustrated in FIG. 1 is an original welded part image (a welded part image by arc light emitted from arc plasma) taken through a neutral density filter. A welded part image 2 illustrated in FIG. 2 is a high-temperature emphasized welded part image in which a high-temperature part is emphasized. The welded part image 3 illustrated in FIG. 3 is a non-high temperature welded part image that does not emphasize the high temperature part. 1-3, the right direction shows a welding direction.
The high-temperature emphasized welded part image 2 and the non-high-temperature welded part image 3 may be obtained from the original welded part image 1 by image processing, or may be taken through a wavelength filter (optical filter). When the high-temperature emphasized welded portion image 2 and the non-high-temperature welded portion image 3 are obtained from the original welded portion image 1 by image processing, the original welded portion image 1 is a color-captured original welded portion image.

The inventors first have
(1) It was found that there is a correlation between the bead width value and the clearance value.
The width of the bead formed by arc welding can be detected from, for example, the original welded part image 1 shown in FIG. 1 obtained by photographing the welded part during welding of the workpieces. Since the bead has a high temperature, it is desirable to use the high-temperature emphasized welded part image 2 in which the high-temperature part shown in FIG. 2 is emphasized. Here, the high-temperature emphasized welded part image 2 is used.
According to the experiments and examinations by the present inventors, for example, the maximum value of the vertical dimension in a region having a luminance value equal to or higher than a certain value in the high-temperature portion-emphasized welded portion image 2 is the bead width value BW (see FIG. 2). When this was done, a correlation as shown in FIG. 4 was obtained between the bead width value BW and the gap value G. In FIG. 4, the vertical axis represents the bead width value BW, the horizontal axis represents the gap value G, and the graph 21 represents the bead width value BW with respect to the gap value G obtained by experiments. 22 is a graph showing the relationship between the clearance value G and the bead width value BW as a straight line. As can be seen from FIG. 4, as the gap value G increases, the bead width BW decreases.
If the correlation (graph 21 or straight line 22) between the bead width value BW and the gap value G is used, the gap value G is detected by detecting the bead width value BW, and further the gap value G It is possible to seek changes.
If the control is performed to correct the welding condition, mainly the welding speed V (corrected by the speed ΔV) according to the change in the gap value G, the welding quality is improved.

next,
(2) In arc welding, as can be seen from the welded portion images 1 to 3 shown in FIGS. 1 to 3, particularly as seen from the non-high temperature welded portion image 3 shown in FIG. The sharp shape 3a (refer FIG. 3) is shown toward right direction in FIG.
According to the experiments and examinations of the present inventors, the sharp shape 3a is generated by a groove, and the tip position 3b of the sharp shape 3a is a groove position, that is, an actual welding position (actual welding position on the X axis). I found out.
Therefore, if the tip position 3b of the pointed shape 3a is detected and this tip position 3b is compared with a preset welding position (X coordinate: each position on the weld line), the actual welding position X with respect to the set welding position X is determined. The amount of deviation (target deviation) ΔX can be detected. If the deviation ΔX is eliminated and control is performed to correct the welding position X by the deviation ΔX so that welding is performed in accordance with the actual welding position X, the welding quality is improved.
The tip position 3b of the pointed shape 3a may be detected from the welded portion images 1 and 2 shown in FIGS. 1 and 2, but is preferably performed from the non-high temperature welded portion image 3 shown in FIG. This is because if the non-high temperature welded part image 3 is used, the tip position 3b can be detected more accurately without being affected by high-temperature spatter generated during welding.
The method of the present invention improves the welding quality based on the above findings (1) and (2), and the embodiment will be described below.

FIG. 5 is a block diagram showing an overall configuration of an embodiment of a welding apparatus to which the method of the present invention is applied.
As shown in this figure, the welding apparatus according to the present embodiment is an apparatus for arc welding a workpiece W (W1, W2) made of, for example, a steel plate, which is an object to be welded. An optical filter 62 and an image processor 63 are provided.

The welding apparatus main body 5 includes a welding torch 51, an arc welding robot 52, a robot control device 53, and an arc welding power supply device 54, and basically uses the arc welding robot 52 to provide an arc welding apparatus. It is a common one when configuring.
For example, the robot controller 53 pre-describes the position and orientation (orientation) of the arm of the arc welding robot 52 in the three-dimensional space, the start and end of arc welding, welding conditions, and the like, and performs arc welding according to a stored execution program. The robot 52 can be controlled. Moreover, it is comprised so that control which correct | amends a welding position and welding conditions, and the welding speed V here can be performed during arc welding.
Further, the arc welding power source device 54 measures the arc current I during welding, compares the measured value (actually measured value) with a set value, and if there is a change, gives the change amount ΔI to the robot controller 53 for correction. It is configured so that it can be controlled.
The position in the three-dimensional space is represented by coordinates (X, Y, Z) on the X, Y, and Z axes. Here, the Y axis indicates the welding direction, the X axis indicates the direction crossing the welding direction, and the Z axis indicates the height direction of the arm (welding torch 51) of the arc welding robot 52. The workpiece W is also placed on the same three-dimensional space.
The welding conditions include arc voltage E, arc current I, welding speed (robot moving speed) V, and the like.

The camera 61 is directed to the welded portion WZ and takes an image (welded portion image) of the welded portion WZ when welding the workpieces W1 and W2 (hereinafter referred to as workpiece W). Consists of a color camera. In the present embodiment, since the camera 61 is attached to the welding torch 51, a so-called small camera is used so as not to hinder the penetration of the welding torch 51.
The neutral density filter 62 is disposed on the light receiving side of the camera 61 and protects the camera 61 from excessive light or the like. The neutral density filter 62 is attached to the camera 61, for example.

  The image processor 63 fetches the original welded part image 1 (see FIG. 1) from the camera 61, and based on the original welded part image 1, the width of the bead B formed by welding (bead width value BW: see FIG. 2). ) To obtain the gap value G. The apparatus outputs a control signal for correcting the welding condition, here, the welding speed V based on the obtained gap value G (gap value change amount ΔG), the details of which will be described below.

In this embodiment, the image processing processor 63 performs A / D conversion on the original welded part image 1 from the camera 61 and forms a luminance distribution image obtained by digitizing the light intensity at the pixel position for each pixel. The bead width value BW is detected based on the image. For convenience of explanation, the original welded part image 1 also indicates an original welded part image after digitization.
In this embodiment, the bead width value BW is a luminance value (pixel value) that is equal to or higher than a certain value in the high-temperature part-emphasized welded part image 2 (see FIG. 2) obtained by performing red emphasis on the original welded part image 1. In the area having the maximum value, the maximum value of the vertical dimension is taken as the value.
In the image processor 63, data (function formula or look-up table) indicating the correlation between the bead width value BW and the gap value G as shown in FIG. 4 is registered in advance and detected as described above. The gap value G can be obtained from the bead width value BW.
The image processor 63 is configured to output a control signal for correcting the welding conditions, here, the welding speed V so that optimum welding is performed at the gap value G from the gap value G thus obtained. ing.

The image processor 63 is a device that outputs a control signal for correcting the welding position X, and details thereof will be described below.
As illustrated in FIGS. 1 to 3, the welded portion images 1 to 3 show a pointed shape 3 a (see FIG. 3) toward the welding direction (the right direction in FIGS. 1 to 3). The sharpened shape 3a is generated by a groove, and the present inventors believe that the tip position 3b (see FIG. 3) of the sharpened shape 3a becomes a grooved position, that is, an actual welding position (actual welding position on the X axis). Has been found by.

The image processor 63 obtains an arc light image shape 3c formed by a region having a luminance value equal to or higher than a certain value of the non-high temperature welded portion image 3 among the welded portion images 1 to 3. Then, the sharp shape 3a is detected from the arc light image shape 3c, and the tip position 3b of the sharp shape 3a is detected. The tip position 3b is a groove position, that is, an actual welding position X, and the actual welding position X is detected by detecting the tip position 3b.
Then, the tip position 3b of the pointed shape 3a is compared with a preset welding position (X coordinate: each position on the welding line), and a deviation (target deviation) amount ΔX of the actual welding position X with respect to the set welding position X is detected. To do.
The image processor 63 is configured to output a control signal for correcting the welding position X so as to eliminate the detected deviation amount ΔX and perform welding according to the actual welding position X.
Note that the graph representing the “variable” in the block of the robot control device 53 in FIG. 5 merely shows an image, and is not limited to this.

The welding apparatus according to the present embodiment performs arc welding as follows.
That is, the arc welding robot 52 performs arc welding while supplying the welding power source from the arc welding power source device 54 between the welding torch 51 and the welding workpiece W. The arc welding is performed by controlling the arc welding robot 52 according to a welding condition and a welding position (weld line) described in a program executed by the robot controller 53, that is, a preset welding condition.
The welding conditions include an arc voltage E, an arc current I, and a welding speed V. The control related to the welding position is performed with respect to the position of the welding torch 51 with respect to the workpiece W, that is, the coordinates (X, Y, Z) and the direction.

The outline of the arc welding method using the arc welding robot 52 is not particularly different from the general one, but in this embodiment, the following correction control (feedback control) is performed during welding in order to improve the welding quality. Is done.
That is, in FIG. 5, when the arc welding robot 52 starts arc welding under the control of the robot controller 53, the camera 61 directed to the weld WZ passes through the neutral density filter 62 (see FIG. 1). ) Starts shooting. The photographing operation of the camera 61 may be started before starting arc welding.

The image processor 63 captures the original welded part image 1 from the camera 61, forms a digitized luminance distribution image, performs the image processing described below, and transmits the processing result (control signal) to the robot controller 53.
That is, first, the image processor 63 performs red emphasis on the digitized original welded part image 1 to obtain a high temperature part emphasized welded part image 2 (see FIG. 2). Then, for example, the maximum value of the vertical dimension in a region having a luminance value equal to or higher than a certain value in the obtained high-temperature part-emphasized welded part image 2 is measured, and the value is set as a bead width value BW. Then, the gap value G is obtained from data (function formula or look-up table) indicating the correlation between the bead width value BW and the gap value G registered in advance. Then, a control signal for correcting the welding condition, here, the welding speed V is transmitted to the robot controller 53 so that optimum welding is performed at the gap value G from the obtained gap value G.

  Further, the image processor 63 performs blue emphasis on the digitized original welded part image 1 to obtain a non-high temperature welded part image 3 (see FIG. 3). And the arc light image shape 3c which the area | region which has a luminance value more than a fixed value in the obtained non-high temperature welding part image 3 makes | forms is calculated | required, In this arc light image shape 3c, a welding direction (right direction in FIG. 3) is carried out. The sharp shape 3a shown toward the head is detected, and the tip position 3b of the sharp shape 3a is detected. Thereby, the groove position, that is, the actual welding position (actual welding position on the X axis) is detected.

Then, the tip position 3b of the pointed shape 3a is compared with a preset welding position (X coordinate: each position on the welding line), and a deviation (target deviation) amount ΔX of the actual welding position X with respect to the set welding position X is detected. To do. Then, a control signal for correcting the welding position X is transmitted to the robot controller 53 so that the deviation amount ΔX is eliminated and welding is performed according to the actual welding position X.
The robot control device 53 receives the deviation (target deviation) amount ΔX, the gap value variation amount ΔG, and the current variation amount ΔI, and converts them into the position coordinates of the arc welding robot 52, respectively, and the positions X, Z and the speed. A correction command for V (moving direction and moving speed) is sent to the arc welding robot 52.
Thereby, control which corrects welding operation according to the welding situation of work W, especially control which corrects in real time is performed, and welding quality improves, such as forming a good weld bead.

In the above-described embodiment, the case where arc welding is used for welding has been described. However, the present invention is not limited to this. When the present invention is applied to welding other than arc welding, it is a matter of course that a welding robot corresponding to the welding type is used instead of the arc welding robot.
Moreover, although the above-mentioned embodiment demonstrated the case where the part which the workpiece | work W1, W2 overlapped as shown in FIG. 5 was fillet welded, it is not limited only to this.
In the above-described embodiment, a wavelength filter (optical filter) may be added to the light receiving side of the camera, and a high-temperature emphasized welded part image or a non-high-temperature welded part image may be obtained by the same wavelength filter. According to this, it is possible to change the camera from a color camera to a monochrome camera.

  1: Original welded part image, 2: High temperature emphasized welded part image, 3: Non-high temperature welded part image, 3a: Sharp shape, 3b: Pointed tip position, 3c: Arc light image shape, 5: Welding device main body, 51 : Welding torch, 52: arc welding robot, 53: robot control device, 54: arc welding power supply, 61: camera (imaging means), 62: neutral density filter, 63: image processor (image processing means), B: Bead, BW: Bead width value, G: Sheet gap value, W (W1, W2): Workpiece, WZ: Welded part.

Claims (7)

A welding method for welding plates to each other,
Take a picture of the weld,
The bead width value is detected based on the photographed weld image,
Obtain the value of the gap between the plates to be welded from the detected bead width value,
A welding method characterized by performing welding while controlling to correct welding conditions based on the obtained value of the gap.   The welding method according to claim 1, wherein the welding condition is a welding speed, and welding is performed while controlling to correct the welding speed based on the value of the plate gap. A welding method for welding plates to each other,
Take a picture of the weld,
Detects the shape of the light image formed by the region having a luminance value greater than or equal to a certain value in the photographed weld image,
The actual welding position is detected from the detected light image shape,
A welding method characterized by performing welding while performing control to correct a welding position by comparing a detected welding position with a set position.   Arc welding is used for welding, The welding method of any one of Claims 1-3 characterized by the above-mentioned.   The welding method according to claim 4, wherein the light image shape is an arc light image shape. A welding device for welding a plate and a plate by controlling a welding robot by a robot control device,
Photographing means for photographing an image of the weld;
A bead width value is detected based on the welded part image from the photographing means, a value of a gap between the plates to be welded is obtained from the detected bead width value, and a welding condition is corrected based on the obtained value of the gap. And / or an actual welding position is detected from the optical image shape in the welded portion image, and the detected welding position is compared with the set position to output a control signal for correcting the welding position. Image processing means,
A welding apparatus, wherein the robot control apparatus receives a control signal from the image processing means and performs welding while controlling the arc welding robot. The welding condition is a welding speed,
The welding apparatus according to claim 6, wherein the image processing unit outputs a control signal for correcting a welding speed based on the value of the gap.