JP2003260571A - Friction stir welding method - Google Patents

Abstract

(57) [abstract] (with correction) [Problem] For a bending along a longitudinal direction of a joining line formed at a butt surface, a friction stir welding tool can accurately track the joining line, and poor joining at a joining portion. Should not occur. SOLUTION: An extruded aluminum alloy material to be joined 1
A round shape having a radius of 0.3 to 0.7 mm is provided at the corner 11 at the upper end of the joint, the molds 1 are abutted with each other, and a wide groove formed above the joint 6 is irradiated with illumination light from directly above. ,
The junction 6 is photographed from directly above with a CCD camera,
The image of the shadow 10 of the joint line photographed by the camera is image-processed by the image processing device, the shift amount of the joint line in the image from the reference line is calculated by the calculating means, and the shift amount is transmitted to the servo amplifier. Then, the servo motor is feedback-controlled so that the friction stir welding tool is accurately traced to the center of the gap 10 of the welding line.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a friction stir welding method for tracing a butt joint line with a welding tool for abutting friction stir welding of aluminum alloy extruded mold materials, etc. By doing so, it is possible to reliably prevent the occurrence of a joining line tracking error of the joining tool, and to avoid a joining failure due to a joining line tracking error.

[0002]

2. Description of the Related Art For example, aluminum alloy plate materials, extruded mold materials and the like used for side plates and floor plates of railway vehicles are
The joint is extremely long. Therefore, when such a long plate material is extruded, the formed plate material is slightly deformed in the longitudinal direction. In order to bring the plate materials into contact with each other by friction stir welding, for example, ribs projecting from the back surface are pressed from opposite sides of the plate materials, and the plate materials are tightened so that there is almost no gap between the contact surfaces, and temporary attachment is performed in this state. However, if there is a subtle deformation in the longitudinal direction that can be made when the plate material is molded,
Due to the convenience of the mating partner, when the mold materials are forcibly bent and joined together, the abutting surfaces draw various curves. It is not easy to accurately track such a curved butt joint line with a welding tool, and for this reason an optical profile is adopted for tracking.
As shown in Fig. 7, there are many streaky (thin black lines) scratches on the surface of the plate material, such as when the plate material is manufactured. , Immediately after passing through the temporarily attached part, it becomes difficult to distinguish the joining line from the scratched line, and the copying to the joining line does not work well, so the welding tool frequently deviates from the joining line, and the work is done each time. There is no choice but to stop and correct the trajectory. Therefore, in order to trace the butt joint line while optically detecting it, first, the shadow of the butt face must be reliably captured on the image. However, it is desirable to set the abutting surface to be minute or zero, so the shadow of the abutting surface becomes unclear or unclear, so it is extremely difficult to reliably capture the joining line and accurately track it. is there. In particular, when temporarily attached, the joining line seems to be interrupted, so when passing through this temporary attachment position as described above,
There is a risk that streak-like scratches on the surface of the plate will be mistakenly caught as a joining line and the scratches will be traced. Also, the shadow of the joining line formed by the abutting surfaces is captured as sharply as the image of the CCD camera, and the image is processed to make a copy. However, when the gap between the joining lines is zero, the joining lines are continuous. It may not be possible to capture it as a line, and for example, the corner of the abutting surface of the plate material is a minute R, and the width of the minute R is 0.05 m.
Even if a groove of about m is formed, if the joining line is photographed by the CCD camera from the position shown in FIG. 5, the joining line can be captured as a clear image line as shown in FIG. On the other hand, on the other hand, it is not easy to discriminate the shadow of a fine streak-like scratch on the surface of the plate material or the shadow of a scratch line formed especially on a temporarily attached place. On the other hand, in order to accurately trace the joining line, it is necessary to clearly capture the joining line as a thick black line to some extent, and perform image processing to trace this.

[0003]

SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned problems and to make a CCD camera clearly photograph a joining line formed by abutting an aluminum alloy plate material, an extrusion die material, etc. For the purpose of accurately tracking the bond line, the shadow of the bond line on the image from the CCD camera is image-processed so that the bond line can be traced accurately so that the bond line is a clear line over the entire length. It is to devise the method of detecting the joining line so that it can be captured.

[0004]

[Measures taken to solve the problem]

Means for Solving Problem 1 Means taken for solving the above problems
Is a friction stir welding method in which the XYZ position of the friction stir welding tool is controlled by a servomotor, and the welding line is used to trace the welding lines of the welded portions where the aluminum alloy extruded die members are abutted to each other by the welding tool. It is composed of the following (a), (b), (c), and (d). (A) Aluminum alloy extruded molds having a radius of 0.3 to 0.7 mm provided at the upper end corners of the aluminum alloy extruded molds to be joined together by abutting against each other,
A wide groove is formed at the abutting portion by the rounded portion of the upper end corner. (B) Illumination light is applied to the abutting portion from directly above and an image is taken from directly above with a CCD camera.
The image of the shadow of the groove line photographed by the CD camera is image-processed by the image processing device, and the deviation amount of the groove line in the image from the reference line on the image is calculated. To the servo amplifier and feedback control the servo motor to trace the joining line with the joining tool.

[0005]

[Function] By forming a roundness with a radius R of 0.3 to 0.7 mm at the corner of the upper end of the aluminum alloy extruded die member to be friction stir welded, and by abutting the aluminum alloy extruded die members to each other, the abutting end faces are in close contact with each other. However, the gap is zero, and a groove having a width of 0.6 mm or more and a depth of approximately 0.3 mm is formed on the butting upper surface by the roundness. Then, by illuminating the groove formed by the rounded portion with the illumination light from directly above and photographing the CCD light from directly above, the groove can be clearly projected on the image. Since the rounded sizes of the extruded aluminum alloy die members are substantially equal to each other, the centers of the grooves formed by the rounded portions coincide with the abutting surfaces of the left and right die members. In addition, since the illumination light is irradiated from directly above the groove formed by the roundness and the image is taken from directly above, regardless of the condition of the part to be photographed, such as the presence or absence of bending of the joining surface, with a substantially constant strong contrast, The line of the groove can be photographed with a CCD camera as a clear and thick shadow. In addition, in the surface near the joint surface, innumerable surface scratches are formed at the time of forming the aluminum alloy extrusion die material, but these surface scratches are relatively shallow, and the contrast of the image is more than that of the image of the groove line. Is also quite weak. Therefore, when the captured image is binarized by the image processing apparatus, the surface flaw is erased from the binarized image data by setting the threshold value to an appropriate value, and the line of the groove is removed. Only the image of is left as the binarized image data. Therefore, the welding tool can accurately trace the line of the groove regardless of the presence or absence of the line of the processing flaw on the material surface. Although the line of the groove on the image data disappears at the temporary attachment portion, the abutting surface is traced while roughly running by a separate control program during this time.

[0006]

Means 2 for solving the above problems is to control a position of an XYZ direction of a friction stir welding tool by a servomotor, and to use a welding tool to form a joining line of a joining portion where aluminum alloy extruded die members are butted to each other. Assuming the friction stir welding method of tracing and joining, the following (a),
It is composed of (b), (c) and (d). (A) The upper end corners of the aluminum alloy extruded die members to be joined by butting are chamfered by 0.3 to 0.7 mm, the aluminum alloy extruded die members are butted to each other, and a wide groove is formed at the butted portion by the chamfered portion. (B) Illumination light is applied to the abutting part from directly above and the image is taken from directly above with a CCD camera. (C) CCD
The image of the shadow of the line of the groove photographed by the camera is image-processed by the image processing device, the deviation amount of the groove line in the image from the reference line on the image is calculated, and (d) the deviation amount is calculated. Sending to a servo amplifier and feedback control of a servo motor to trace a joining line with a joining tool.

[0007]

The action of the solving means 2 is the same as that of the solving means 1.

[0008]

Embodiment 1 In Embodiment 1, in the solving means 1 or the solving means 2, the image of the shadow of the joining line photographed by the CCD camera is image-processed by an image processing device, and the image in the image-processed image is processed. Calculate the edge position of the groove line, calculate the amount of deviation of the edge position from the reference line on the image,
That is, the shift amount is transmitted to the servo amplifier and the servo motor is feedback-controlled.

[0009]

The edge of the groove can be clearly captured on the image data by photographing the line of the groove just before joining with the CCD camera and binarizing the image with a predetermined threshold as a reference. The deviation amount of the edge position on the image data after the binarization processing is calculated with respect to the reference line on the image, and based on the deviation amount, control is performed so that the welding tool accurately tracks the edge. can do.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. This embodiment has a thickness of 4.5.
The aluminum alloy plate materials 1 and 1 having a length of 20 mm and a length of 20 mm are butted against each other, and the abutted joints 6 are friction stir welded. The welding is performed by using a welding pin 2 having a diameter of 5 mm at a rotation speed of 1750 rpm and an advance speed of 600 mm min
This is what you do. Further, the aluminum alloy plate materials 1 and 1 are formed with a rounded portion 11a having a radius R = 0.5 mm as shown in FIG. A wide groove is formed in the joined portion 6 formed, and a wide gap 10 is formed above the butting portion 6. The welding pin 2 is attached to the rotary cylinder 3, and the rotary cylinder 3 is rotatably provided below the frame 5 that constitutes the friction stir welding tool M provided with the traveling wheels 4 and 4. Has been. An image of the joining line of the illumination lamp 7 and the joining portion 6 which illuminates the joining portion (the gap 10) with illumination light from directly above the predetermined position on the front side in the traveling direction of the frame body 5 is taken from directly above. A support member 9 equipped with a CCD camera 8 is attached. Then, the illumination lamp 7 is arranged so that the joint portion 6 can be illuminated from directly above, as described above.
The CCD camera 8 is arranged so as to take an image of the junction 6 at a position where the illumination light is emitted from the illumination lamp 7 from directly above. The horizontal distance L between the CCD camera 8 and the joining pin 2 is 200 mm, but there is no particular inconvenience in allowing the joining pin 2 to accurately follow the joining line without making this distance too short.

Further, the friction stir welding tool M moves along the abutted welded portion (or welded line) 6 of the aluminum alloy sheet 1 having rounded portions 11a at the corners of the upper end to be welded. At this time, the illumination lamp 7 irradiates the wide groove of the joint portion 6, the reflected light having low luminous intensity is photographed from directly above by the CCD camera 8, and the images are sequentially taken into the image processing apparatus. The range of the image captured by the image processing device is
It is about 3 mm in the traveling direction and about 20 mm in the width direction. In this image, the gap 10 of the joint portion 6, that is, the line of the groove formed by abutting the roundness formed at the corner of the upper end is shown in FIG. 3 (photographed, 3 mm in the traveling direction,
The image clearly appears in the captured image, such as an image of a 20 mm range captured in the width direction. As can be seen in FIG. 3, a 0.5 mm roundness 11 provided at the corner of the upper end of the butt end face.
Since a groove having a width of a and a center depth of approximately 0.5 mm is formed, a thick line is captured as a clear image with a relatively high contrast. On the other hand, although the surface flaw near the abutting surface is also photographed in the same manner, the contrast of the image of the line of the surface flaw of the aluminum alloy plate material in this example is at most 2 that of the image of the groove line.
It is clear from the measurement results that it is less than%.

Therefore, the image taken by the CCD camera is
When the contrast of the image of the groove line is 100,
When this photographed image is binarized based on the threshold value of 55, the line formed by the groove appears as a black thick line 12. On the other hand, all other lines due to scratches on the end surface of the aluminum alloy sheet 1 are erased. Therefore, only the groove line 12 is extracted as image processing data on the image processed image data. When tracing the joining line, the center of the above line on the image processing data is calculated and C
The above line can be traced by comparison with the reference position provided in the PU, but the position of the edge of the line on the image data is compared with the reference of the CPU so as to be traced. Control. The tracking control technique itself is merely an application of a general guide control technique using a guide wire.

In addition, the radius R =
Aluminum alloy plate 1,1 with 0.5mm roundness
The actual tracking accuracy of the joining pin 2 tracing the joining line was confirmed for the aluminum alloy plate materials 1, 1
Irrespective of whether or not the joining line is bent due to the deformation of the end portion in the longitudinal direction, the image of the joining line taken by the CCD camera 8 is clear with a substantially constant contrast despite the length of the joining line being as long as 20 m. It was confirmed that the tracking error of the joining pin with respect to the abutting surface was almost zero, and there was no joint failure due to the displacement of the joining pin with respect to the center of the gap.

[0014]

As described above, according to the present invention, when aluminum alloy sheet materials and the like are butted against each other and joined, the corners of the joined ends are rounded or chamfered, and the upper surface of the butted joint part is joined. Form a groove with a predetermined width and a predetermined depth on the joint, and irradiate the joining portion with illumination light from directly above,
By photographing this from directly above with a CCD camera, it can be reliably photographed as a shadow of a clear line having a predetermined width and a predetermined contrast. Then, by subjecting this to image processing, other lines on the image due to surface scratches and the like can be erased, and only the line of the above groove is left as image data, and the joining line can be reliably traced based on this. . Since the joining pin is traced to the joining line based on the image data as described above, the joining pin can accurately trace the joining line regardless of the presence or absence of the joining line defect due to surface scratch or temporary attachment. Therefore, it is possible to surely avoid the defective joint due to the displacement of the joint pin from the joint line. Further, since the corners of the end portions of the aluminum alloy plate material are simply rounded or chamfered, there is almost no special increase in cost for that purpose.

[Brief description of drawings]

FIG. 1 is a conceptual perspective view showing a state in which aluminum alloy sheet materials are joined by a friction stir welding tool by the friction stir welding method of the present invention.

FIG. 2 is a schematic enlarged perspective view showing a state in which aluminum alloy sheet materials having rounded corners of the present invention are butted against each other.

FIG. 3 is an image obtained by abutting the aluminum alloy plate materials embodied in the present invention with each other and photographing a part of the joining line formed by the abutting with a CCD camera.

FIG. 4 is a block diagram of a conventional image processing system.

FIG. 5 is a schematic side view of a conventional friction stir welding apparatus.

[FIG. 6] is a view showing that the conventional plate members are butted against each other, and a part of the joining line formed by the butting is C
It is an image captured from a diagonal direction with a CD camera.

FIG. 7 is a schematic plan view showing a part of a state where the extruded plate members are abutted against each other and pressed against each other with a vise, and a predetermined portion of the butt joint is temporarily attached.

[Explanation of symbols] M: Friction stir welding tool 1: Aluminum alloy plate material 2: Joining pin 3: rotating cylinder 4: Traveling wheel 5: frame 6: junction 7: Lighting 8: CCD camera 9: Support member 10: Bond line gap (shadow of bond line) 11: Corner 11a: roundness 12: Groove line

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Claims (3)

[Claims] 1. A friction stir welding method in which the XYZ direction position of a friction stir welding tool is controlled by a servomotor, and the welding line is used to trace the joining line of the butt joints of the aluminum alloy extruded die members with each other. Aluminum alloy extruded mold members having a radius of 0.3 to 0.7 mm provided at the upper end corners of the aluminum alloy extruded mold members to be butt-joined are butted against each other, and a wide groove formed by the rounded portion at the upper end corner portion at the butted part. Image is formed by directly illuminating the abutting portion with illumination light from directly above, and the CCD camera captures the image from directly above. The image of the shadow of the groove line captured by the CCD camera is image-processed by an image processing device, and the image is processed. Calculate the amount of deviation of the groove line in the image from the reference line on the image, transmit the amount of deviation to the servo amplifier, and A friction stir welding method characterized in that the welding line is traced by a welding tool by controlling the welding. 2. A friction stir welding method in which the XYZ positions of the friction stir welding tool are controlled by a servomotor, and the welding line is used to trace the joining lines of the butt joints of the aluminum alloy extruded die members to each other. Chamfering 0.3 to 0.7 mm at the upper end corners of the aluminum alloy extruded die members to be joined by butting, but abutting the aluminum alloy extruded die members to each other, and forming a wide groove by the chamfered portion at the butted portion, Illumination light is applied to the abutting portion from directly above and the image is taken from directly above by the CCD camera, and the image of the shadow of the line of the groove taken by the CCD camera is image-processed by the image processing device, and the groove in the image is processed. The amount of deviation of the line from the reference line on the image is calculated, and the above amount of deviation is transmitted to the servo amplifier to feedback control the servo motor. FSW method for causing to track the joint line in welding. 3. A shadow image of a joining line photographed by the CCD camera is image-processed by an image processing device, and an edge position of the groove line in the image-processed image is calculated to obtain the edge position of the edge position. The friction stir welding method according to claim 1 or 2, wherein a deviation amount from a reference line on the image is calculated, the deviation amount is transmitted to a servo amplifier, and the servomotor is feedback-controlled.