JP3090018B2 - Method and apparatus for manufacturing welded pipe - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for manufacturing a welded pipe using laser light.

[0002]

2. Description of the Related Art In recent years, a welding pipe has been manufactured using a laser beam emitted from a laser oscillator. FIG.
1 is a schematic perspective view showing a state where a welded pipe is manufactured by laser welding. The band-shaped metal plate 1 is moved in the length direction of the band-shaped metal plate 1 indicated by an arrow, and the band-shaped metal plate 1 is curved so that both side edges in the width direction are opposed to each other to form an open pipe shape. By rotating the squeeze rolls 2 and 2 facing each other with the formed open pipe interposed therebetween, the end faces of both side edges of the open pipe are brought into abutment.

Further, a strip-shaped metal plate (hereinafter referred to as a material to be welded) 1
A high-frequency heating is performed by the heating coil HC at a position separated from the end surface abutting portion W by an appropriate length in the upstream direction (the direction opposite to the arrow) of the workpiece 1 in the moving direction, and heat is input to the end face of the workpiece 1 to be preheated. I do. The laser beam L is applied to the end face abutting portion W formed by preheating.
By irradiating B, the end-face abutting portion W is heated to a high temperature to weld the end-face abutting portion of the workpiece 1 to continuously produce a welded pipe.

In such a method of manufacturing a welded pipe by laser welding, a welded pipe having a narrow molten bead width can be manufactured due to a small spot diameter of a laser beam. If irradiation failed,
Poorly welded portions where the end contact portions are not completely welded are generated. Therefore, it is necessary to make the irradiation position of the laser beam accurately follow the end face abutting portion. A method for causing the irradiation position of the laser beam to follow the end face abutting portion of the workpiece, that is, a seam copying control method is disclosed in Japanese Patent Publication No. 4-31799.

FIG. 12 is a schematic perspective view of the method for controlling the seam copying welding. The workpiece 1 is moved in the direction of the arrow while the end faces of the workpiece 1 bent into an open pipe shape are abutted by the squeeze rolls 2, 2, and the end face of the workpiece 1 is joined from the processing head 3. The portion W is irradiated with the laser beam LB. Also, before the end contact portion W,
Two positions separated by a predetermined distance in the moving direction of the workpiece 1 are set as detection positions, and the edges A ₁ , B at the detection positions
Midpoint M ₁ of _1, a displacement vector from the welding reference line L measured for people midpoint M ₂ each edge A _2, B _2, the distance from the end surface abutting portion of the detection position of each of the displacement vector and each Based on D ₁ , D ₁ + D ₂ , the deviation of the end face abutment portion W from the welding reference line L is calculated, and control is performed to match the irradiation position of the laser light LB to the end face abutment portion W accordingly.

[0006]

However, in the conventional seam copying control described above, there are many cases where some disturbance element affects the two detection positions, so that the following error occurs at the end face abutting portion. Occurs. All of these errors are unacceptable considering the accuracy of ± 0.1 mm required for laser welding. That is, the edge of the workpiece 11 bent into an open pipe shape is not necessarily straight due to the scale F and the burrs G as shown in FIGS. Accordingly, the scale F and the burrs G are erroneously detected as edges, and the error increases. In addition, such a scale F
Is constantly generated depending on the material, and burrs G occur frequently (once at about 0.5 m).

Further, a large number of spatters H are generated from the welded portion by laser welding as shown in FIG. When the sputter H passes through the detection position, an edge is erroneously detected and an error occurs. Further, when the sputter H adheres to the processing head, the subsequent scanning control becomes impossible. As described above, the edge of the welded material 11 bent into an open pipe shape is minutely uneven, and even if it is seemingly straight, when the edge is detected at only two detection positions, , The error increases.

Further, in the seam copying control described above,
The edge of the material to be welded 11 is regarded as a straight line, and an intersection point where the straight line intersects is defined as an end face abutting portion W. However, when the end face abutment portion W changes, the edge of the workpiece 11 bends as follows. That is, the edge of the material to be welded 11 is constrained by a final forming roll (fin pass roll) (not shown) on the upstream side of the end face abutting portion W as shown in FIG. From the line L, the position is the same size. on the other hand,
The portion where the both edges abut against each other is restrained by a squeeze roll (not shown), but the position at that time varies due to factors such as bending (camber) of the material to be welded. That is, the position of the end face abutting portion changes with respect to the welding reference line L.

Therefore, the material to be welded between the two rolls is bent as shown in FIGS. 17 and 18 under compression and tension. Therefore, as shown in FIG. 18, when an edge is a straight line and an intersection of the straight line is obtained, an error α occurs.
This error α is unacceptable in laser welding that follows the end face abutting portion with high accuracy. Incidentally, the degree of the curvature of the edge depends on the diameter, thickness, material strength and the like of the open pipe-shaped material to be welded. Further, as the end face abutting portion deviates from the welding reference line L, the end face abuts more. Therefore, the magnitude of the error varies depending on the situation. For example, when the deviation of the edge from the welding reference line is about 5 mm, the error α reaches about 0.7 mm, and high-precision laser welding is performed. There is a problem that is impossible.

[0010] In view of the above problems, the present invention provides a method for receiving a laser beam without being affected by the asymmetry of the edge, the curvature of the edge, and the unevenness of the edge of the welded material bent into an open pipe shape. An object of the present invention is to provide a method and an apparatus for manufacturing a welded pipe, which can accurately irradiate an end contact portion of a welding material and irradiate the welded pipe with extremely high welding accuracy.

[0011]

According to a first aspect of the present invention, there is provided a method for manufacturing a welded pipe, comprising: moving a strip-shaped metal plate in a longitudinal direction thereof; The pipes are curved so that the edges face each other to form an open pipe, and the edges on both sides are high.
Preheated by frequency heating and abuts the end faces of both preheated edges
Is, in the manufacturing method for welding pipes to weld the abutment of the end face by irradiating a laser beam to abutment of the end face, both side ends in the moving direction upstream side of the band-shaped metal plate from abutment of the end face
The wavelength of the band-shaped metal plate including the edge is 450 nm by the imaging means.
Dimensionally imaged by the optical exceeding extracts a large number of edge data indicating the edge positions of people the both side edges respectively captured, extracted curves approximating each side edge based on the edge data Me and the edge approximate the curve determined, obtain the intersection of each side edge edges approximate curve that corresponds to the irradiation position of the laser light based on the intersection of the data obtained, intersecting with the moving direction It is characterized by moving in the direction.

[0012]

The method of manufacturing a welded pipe of the invention according to claim 2, the edge of the band-shaped metal plate, wherein the imaging by blocking light of wavelengths below 450nm or less.

[0014]

According to a third aspect of the present invention, there is provided an apparatus for manufacturing a welded pipe , comprising: moving a strip-shaped metal plate in a longitudinal direction thereof;
The metal plate is curved so that both edges in the width direction face each other.
To form an open pipe and heat the edges on both sides with high frequency
By preheating, butting the end faces of the preheated side edges,
Irradiation of laser beam to the abutting part of the surface to weld the abutting part of the end face
In the apparatus for manufacturing a welded pipe, a band is
Strip including both side edges on the upstream side in the moving direction of the metal plate
Plane imaging of a metal plate with light with a wavelength exceeding 450 nm
Imaging means for performing the processing, and data captured by the imaging means.
A large number of edge data indicating the edge position of each side edge is extracted.
Means for exiting and two edges corresponding to each extracted side edge
Calculate the approximate curve and find two edge approximations corresponding to each side edge
Means for finding the intersection of lines and based on the data of the found intersection
The laser light to intersect the direction in which the metal strip moves.
Means for moving in a direction .

According to a fourth aspect of the present invention, there is provided an apparatus for manufacturing a welded pipe, comprising:
An optical filter that does not transmit light having a wavelength of 450 nm or less is provided.

According to a fifth aspect of the invention, there is provided an apparatus for manufacturing a welded pipe, wherein the imaging means has an optical characteristic of not receiving light having a wavelength of 450 nm or less.

[0018]

According to the present invention, an image of an edge of the band-shaped metal plate facing in the width direction is taken at an upstream position in the moving direction of the band-shaped metal plate. The image captured by the image processing for extracting a large number of edge data indicating the both side edges located in the strip-shaped metal plate. Calculates the edge approximate curve data s both side edges respectively by extracted edge data, the edge approximate the curve that corresponds to the one side edge, the intersection of the edge approximate the curve that corresponds to the other side edge The calculated intersection is used as an abutting portion of the end face , and the laser beam irradiated on the strip-shaped metal plate is moved in a direction intersecting the moving direction of the strip-shaped metal plate based on the calculated intersection data. When the thickness of the band-shaped metal plate is large, high-frequency heating is performed to preheat the band-shaped metal plate. Thereby, the abutment of the end face of the belt-like metal plate, asymmetric both side edges opposed, can be accurately detected without being affected by the curvature and the edge of the unevenness of the edges, to follow the abutment of the end face Laser beam, and high welding accuracy can be obtained.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing the embodiments. [Embodiment 1] FIG. 1 is a schematic configuration diagram of an apparatus for manufacturing a welded pipe according to a first embodiment for carrying out a method for manufacturing a welded pipe according to the present invention. In order to manufacture the welded pipe 10, the material to be welded 11 made of a strip-shaped metal plate is moved in the direction of the arrow while bending it into an open pipe shape. A laser head 12 that irradiates a laser beam toward the end surface abutting portion W is disposed above the end surface abutting portion W of the bent workpiece 11. The laser head 12 is movable in a direction perpendicular to the moving direction of the workpiece 11. Above the upstream position in the moving direction indicated by an arrow, which is separated from the position of the end face abutting portion W by an appropriate length, the imaging area X is set to about 120 to 150 m.
380,000 pixel two-dimensional CCD camera 13 adjusted to m
The light receiving surface is installed at a position 500 mm away from the end face height position of the workpiece 11 with the light receiving surface facing the workpiece 11 side. Note that the CCD camera 13 is fixed so that the horizontal scanning direction of the CCD camera 13 coincides with the direction perpendicular to the moving direction of the workpiece 11.

Thus, the CCD camera 13 can obtain each data of the left and right end faces of the workpiece 11 in one horizontal scan. If the number of horizontal scan lines is 480, each of the left and right edges can be obtained. Edge data of 480 points is obtained. Light sources 14 and 14 are provided on the left and right sides of the CCD camera 13, and the light emitted from the light sources 14 and 14 illuminates the imaging area X and its vicinity. Image data captured by the CCD camera 13 is input to the image processing unit 15 of the personal computer PC. The image processing unit 15 performs image processing on an image based on the input imaging data, and extracts edge data of a required number of edges of the workpiece 11 that has been imaged. The edge data extracted by the image processing unit 15 is input to the calculation unit 16.

The calculating section 16 calculates the curve data indicating the approximate edge curves of the left and right edges based on the input edge data, and calculates the approximate edge curve of the left edge and the approximate edge curve of the right edge. Data of the intersection with the curve is calculated. Intersection data of the intersection calculated and output by the operation unit 16 is input to the output unit 17. The output unit 17 outputs a control signal corresponding to the input intersection data. The control signal CS output from the output unit 17 is input to a drive unit (not shown) that moves the laser head 12, and moves the laser head 12 in a direction orthogonal to the moving direction of the workpiece 11 according to the control signal CS. It is made to let. The projection of light for illumination does not necessarily have to be performed from above, but may be performed from the side or from below.

Next, the operation of laser welding by the laser welding apparatus thus constructed will be described. The material to be welded 11 made of a strip-shaped metal plate is moved in the direction of the arrow while being bent into an open pipe shape, and the material to be welded 11 is irradiated at the laser beam irradiation position.
Are joined to form an end contact portion W. Depending on the preheating state of the workpiece 11, light is projected from the light sources 14 and 14 to illuminate the imaging region X so that the edge of the workpiece 11 can be clearly identified. Then, the imaging area X is imaged by the CCD camera 13, and the imaged data is
Enter 5 Then, the image processing unit performs image processing such as differentiation processing that has an effect of enhancing the brightness of the input image data, and performs the left and right edges A and B of the workpiece 11 in the edge direction. For example, edge data of 20 points (locations) is extracted. When the extracted edge data is input to the calculation unit 16, the calculation unit 16 calculates edge approximate curve data indicating the edge approximate curves of the edges A and B using the input multipoint edge data. I do.

Here, curve approximation will be described. There are many methods for approximating curves. The most common method is polynomial approximation. this is

[0025]

(Equation 1)

This is a method for determining a _i (i = 0 to n) that minimizes the error with respect to the function curve represented by As n increases, a more accurate curve can be obtained. However, if n is too large, the calculation requires a long time, so it is necessary to perform the calculation at some degree of compromise. Here, a case where n = 2 will be described as an example.

FIG. 2 shows edge approximate curves f ₁ and f ₂ based on the calculated edge approximate curve data. In FIG. 2, the horizontal axis x is the moving direction of the workpiece 11, and the vertical axis y is the direction orthogonal to the moving direction of the workpiece 11. The edge approximation curves f ₁ and f ₂ can be represented by f ₁ = a (x−b) ² + c (2) f ₂ = a (x−b) ² −c (3) Then, the calculation unit 16 calculates the intersection P of the edge approximate curves f ₁ and f ₂ using the calculated edge curve data. The intersection P calculated in this way is the intersection of the edge lines A and B of the workpiece 11 and corresponds to the end face abutting portion W (see FIG. 1) of the workpiece 11 to be irradiated with the laser beam. This means that the position data of the end contact portion W has been obtained.

It is also possible to use an approximation method other than the polynomial approximation method to approximate the approximate curve to the actual edge shape of the workpiece. For example,

[0029]

(Equation 2)

A method approximating the above is also effective. However, there are also inappropriate points such as the need to grasp the constants l and m determined by the material to be welded. In other words, it is necessary to select an approximation method that can be reconciled in consideration of these points.

When the intersection data is input to the output unit 17, the output unit 17 outputs a control signal C corresponding to the intersection data.
S is output and input to the laser head 12. Thereby, the laser head 12 moves the workpiece 11 in accordance with the intersection data.
The laser head 1 moves in a direction orthogonal to the
2 properly irradiates the laser light emitted from the end face abutting portion W,
The end contact portion W is to be welded. As a result of such an operation being performed continuously, the laser head 12 follows the end face abutting portion W, and no deviation occurs between the end face abutting portion W and the irradiated laser beam LB, and the welding accuracy is reduced. It can be greatly improved.

Then, by changing the number of edge data extraction points,
When an error between the end face abutting portion and the laser beam irradiation position was actually measured, measurement results as shown in FIGS. 3 and 20 were obtained. FIG. 3 shows an error measurement result at an edge in a stationary state (no disturbance such as burrs). The vertical axis represents the error, and the horizontal axis represents the number of edge data extraction points. As is clear from this figure, as the number of edge data increases, the edge approximation curve more accurately approximates the edge, and the error in edge approximation decreases. The edge data is 2
In terms of point, it can be seen that the error reaches about 0.125 mm.

FIG. 20 is a characteristic diagram showing a measured error variation in the moving state of the material to be welded, which is simultaneously measured for three kinds of data points "4", "16" and "120". In FIG. 20, the vertical axis represents the position of the end face abutting portion, and the horizontal axis represents time. As is clear from FIG. 20, when the number of data points is four, there is a large variation (= 1 mm) in the calculation result of the end face abutting portion position, and a large error occurs due to the influence of burrs and the like.

Here, considering the permissible error between the end face abutting portion W and the laser beam irradiation position, the spot diameter of the laser beam is 0.1 mm.
Since it is 6 mm, the end face abutting portion W needs to be located within the range of 0.6 mm, and the control accuracy of the laser head 12 simply needs to be ± 0.3 mm. But C
Since there are error factors such as an imaging error of the CD camera 13 and a driving error of a servo motor for driving the laser head 12, the optical error needs to be ± 0.1 mm or less. Therefore, as is clear from FIG.
If the edge approximation curve is obtained as a point or more, the error between the end face abutting portion and the laser beam irradiation position can be secured within 0.1 mm,
High welding accuracy can be obtained. As described above, the edge of the material to be welded is approximated by a curve. When the edge is approximated by a straight line, the error is slightly increased, but the welding accuracy can be similarly increased.

FIG. 4 shows the relationship between the number of edge data extraction points and the error of the irradiation position of the laser beam with respect to the end face abutting portion. FIG. 9 is a characteristic diagram comparing the case of approximation. As is clear from FIG. 4, when the edge is approximated by a curve using three or more edge data, the error between the end face abutting portion and the laser beam irradiation position is 0.1 mm at the maximum. On the other hand, when the edge is linearly approximated with three or more edge data, the same error as described above is a maximum of 0.2 mm, which is slightly larger than that when the curve is approximated. Can be greatly enhanced.

Incidentally, in the conventional seam copying control method described above, the error is 0.25 mm as shown in Japanese Patent Publication No. 4-31799. Therefore, according to the present invention, it is apparent that the error between the end face abutting portion and the laser beam irradiation position can be remarkably reduced, and high-precision laser welding is possible. In this manner, when laser welding is performed without preheating the workpiece 11, the light source 14,
The imaging region X is illuminated by 14. When the thickness of the workpiece 11 is large, laser welding is performed by preheating the workpiece 11 by high-frequency heating. In that case, the edge of the imaging range of the workpiece 11 that is glowing red by preheating can be imaged, and the edge can be clearly distinguished.
The laser welding can be performed with high precision by controlling the movement of the laser head 12 in the same manner as in the case of performing the illumination without performing the illumination by the laser beam.

[Second Embodiment] FIG. 5 is a block diagram of a welding pipe manufacturing apparatus according to a second embodiment for carrying out the method for manufacturing a welding pipe according to the present invention. An ultraviolet removal filter 20 is attached to the tip of the imaging lens 13a of the CCD camera 13, and the reflected light of the imaging region X is reflected by the ultraviolet removal filter 20.
Through which the CCD camera 13 receives light. The other configuration is the same as the configuration shown in FIG. 1, and the same components are denoted by the same reference numerals.

FIG. 6 is a transmission wavelength characteristic diagram of the ultraviolet light removing filter 20. The vertical axis represents transmittance, and the horizontal axis represents wavelength. As is clear from FIG. 3, the wavelength of 580 nm is the transmission limit wavelength of the ultraviolet removal filter 20, and there is a wavelength gradient width where the transmittance gradually changes around the transmission limit wavelength of 580 nm. Light having a wavelength equal to or smaller than the lower limit wavelength of the wavelength gradient width is not transmitted, and light having a wavelength equal to or greater than the upper limit wavelength of the wavelength gradient width is transmitted.

Next, the welding operation of the apparatus for manufacturing a welded pipe constructed as described above will be described. Image processing is performed on an image based on the image data captured by the CCD camera 13, an edge approximation curve approximating the edge of the workpiece 11 is calculated, and the intersection of the two edge approximation curves corresponding to each edge is calculated. The operation of controlling the movement of the laser head 12 based on the calculated intersection data and controlling the irradiation position of the laser beam to follow the end face abutting portion W of the workpiece 11 is performed by the welding pipe manufacturing apparatus shown in FIG. Is the same as the welding operation.

When the material to be welded 11 is heated to a high frequency by heating the material to be welded 11 to, for example, 1100 ° C., the spectral characteristics of the metal melting plasma light generated by the red heat are shown in FIG.
As shown in the figure, light having a high light intensity is generated at a wavelength of 480 to 380 nm. The spectral characteristics of the light generated in the glowing portion are as shown in FIG. 8, and light having a high light intensity is generated at a wavelength of 480 nm or more. Therefore,
When the imaging area X is imaged by the CCD camera 13 through the ultraviolet removing filter 20, the CCD camera 13 does not receive the metal-melted plasma light, but receives only the light of the glowing portion at the edge of the workpiece 11 that is glowed by preheating. . Most of the light in the glowing portion is a long-wavelength infrared component having a wavelength of 600 nm or more. Accordingly, the CCD camera 13 clearly captures the shape of the glowed edge of the workpiece 11, and as shown in FIG.
An image with good contrast in which only B is emphasized is obtained.

Even when the material to be welded 11 is not preheated, the edge shape of the material to be welded 11 is clearly imaged by illuminating the imaging region X with a light source that emits light of a long-wavelength infrared component. can do. Thereby,
The edge of the workpiece can be imaged with higher precision, and the approximate edge curve can be more accurately approximated to the actual edge, and the error between the abutting portion of the workpiece and the laser beam irradiation position can be reduced. Can be
The welding accuracy is further improved.

FIG. 10 is a graph comparing the relationship between the position of the CCD camera in the horizontal scanning direction and the density level of the picked-up image when the ultraviolet removal filter 20 is not mounted and when it is mounted. The vertical axis is the image density level, and the horizontal axis is the horizontal scanning direction position. FIG. 10 shows the measurement of the gray level of the image at the position in the horizontal scanning direction corresponding to the line HL shown in FIG. 9 in the captured image. As shown in FIG. 10, when the ultraviolet removal filter 20 is attached, the difference in the gray level of the image is small, but by attaching the ultraviolet removal filter 20, 480 to 380 n
When the S / N ratio is increased so as not to receive light having a wavelength of m, the difference in the gray level of the image increases, and
It was confirmed that the edge of the image could be clearly imaged. Therefore, the accuracy of the edge approximation curve that is approximated using the edge data can be increased, and thereby, the end face abutting portion W of the workpiece 11 can be improved.
In this case, the error between the laser beam and the irradiation position can be reduced.

[Embodiment] The imaging area X is illuminated,
In the former manufacturing method of manufacturing a welded pipe by laser welding the end face contact portion W of the material to be welded 11, the moving speed of the material to be welded 3 is 3 to 20 m / min, and the outer diameter of the welded pipe to be manufactured. Is 406.9 to 609.6 mm, and when the material to be welded is preheated, the heat input temperature is 1000 ° C. or less. Also,
In the latter manufacturing method of manufacturing a welded pipe by irradiating the end face abutting portion W of the workpiece 11 without illuminating the imaging region X, the moving speed of the workpiece 11 is 3 to 10 m / min. The outer diameter of the welded pipe to be used is 406.9-609.6m
m, the heat input temperature for preheating the material to be welded 11 is about 1100 ° C.

FIG. 21 is a characteristic diagram showing an evaluation test result of the followability of the end face abutting portion. When a test was conducted by applying the apparatus of the present invention to a test welded pipe mill, it was found that extremely good followability was obtained. As an evaluation test method, irradiation and non-irradiation of laser light were repeated at 10-second intervals, and the amount of deviation between the end face abutting portion and the laser light at the start of irradiation or at the end of irradiation was measured with a loupe. As a result, as shown in FIG. 21, it was confirmed that the allowable deviation of the end face abutting portion within ± 0.3 mm could be followed with an accuracy of ± 0.1 mm.

[Conditions] Illumination Open pipe diameter 457.2φ Heat input temperature 800 ° C. FIG. 19 shows the behavior of the end face abutting portion, where the vertical axis represents displacement and the horizontal axis represents time.

In the embodiment of the present invention, the ultraviolet removing filter is used so as to clearly image the edge of the material to be welded. However, similar light transmission characteristics, ie, 450 nm or less, are used without using the ultraviolet removing filter. Which does not receive light of wavelength
Similar effects can be obtained by using a D camera.

[0047]

As described above in detail, according to the present invention, the position on the upstream side in the moving direction of the band-shaped metal plate from the abutting portion of the end surface of the band-shaped metal plate formed in the shape of an open pipe, which is a welding point, is planar.
Imaged, the imaging was many shown edge positions of both side edges respectively <br/> the edge data extracted for the end approximating the respective edges facing with extraction large number of edge data moving an edge approximation curve calculated Me, obtain the intersection of each edge approximate curve that corresponds to the edge of, on the basis of the intersection data obtained in a direction intersecting the irradiation position of the laser beam in the direction of movement of the belt-like metal plate since so as to be irradiated with a laser beam with high precision abutment of the end surface.

In the case where the opposite edge is imaged through the optical filter or by the imaging means that receives light having the same transmission characteristics as the optical filter, the edge can be more accurately imaged, and It is possible to provide a method and an apparatus for manufacturing a welded pipe that can irradiate a laser beam with higher accuracy and have extremely high welding accuracy. Accordingly, the present invention greatly contributes to the industrial world, for example, it is possible to eliminate weld defective spots at all, and to manufacture a welded pipe with remarkably high quality.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a first embodiment of a welded pipe manufacturing apparatus for performing a welded pipe manufacturing method according to the present invention.

FIG. 2 is an edge approximation curve diagram that approximates an edge.

FIG. 3 is a graph showing a relationship between an edge data extraction score and an error.

FIG. 4 is a graph comparing the relationship between the number of edge data extraction points and an error when the edge is approximated by a straight line and when the edge is approximated by a curve.

FIG. 5 is a schematic configuration diagram of a second embodiment of a welding pipe manufacturing apparatus for performing a welding pipe manufacturing method according to the present invention.

FIG. 6 is a transmission wavelength characteristic diagram of an ultraviolet removal filter.

FIG. 7 is a characteristic diagram showing the relationship between the wavelength of the molten plasma light and the light intensity.

FIG. 8 is a characteristic diagram showing the relationship between the wavelength of light in the red-hot region and the light intensity.

FIG. 9 is a diagram showing an image obtained by imaging opposite edges of a strip-shaped metal plate.

FIG. 10 is a graph showing a change in a gray level of an image with respect to a position in a horizontal scanning direction.

FIG. 11 is a perspective view showing a state in which a welded pipe is manufactured using laser light.

FIG. 12 is an explanatory diagram of a conventional seam copying control method.

FIG. 13 is a schematic enlarged view of an edge of a material to be welded.

FIG. 14 is a schematic enlarged view of an edge of a material to be welded.

FIG. 15 is a schematic view of the upper surface of a material to be welded during welding.

FIG. 16 is a state diagram of an edge of a material to be welded.

FIG. 17 is a state diagram of an edge of a strip-shaped metal plate bent into an open pipe shape.

FIG. 18 is an explanatory diagram in which a deviation between an end face abutting portion and a straight line passing through an intermediate point occurs.

FIG. 19 is a graph showing the behavior of the edge of the strip-shaped metal plate.

FIG. 20 is a characteristic diagram in which a material to be welded is moved and an error variation in the position of the end face abutting portion is measured.

FIG. 21 is a characteristic diagram showing a change in a deviation between a laser beam irradiation position and an end face abutting portion.

[Description of Signs] 10 Welded pipe 11 Strip-shaped metal plate (material to be welded) 12 Laser head 13 CCD camera 14 Light source 15 Image processing unit 16 Operation unit 20 Ultraviolet removal filter W End face abutting part A, B Edge

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Taketo Nogami 1850 Minato, Wakayama-shi, Wakayama Sumikin Control Engineering Co., Ltd. (56) References JP-A 7-1167 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B23K 26/00-26/42 B21C 37/08

Claims (5)

(57) [Claims] 1. A by moving the strip-shaped metal plate in the longitudinal direction, a strip-shaped metal plate, to form an open pipe shape by curved so that the both side edges in the width direction opposing the both side edges Hangzhou
Preheating by wave heating, butted end faces of both preheated edges
So, in the manufacturing method for welding pipes to weld the abutment of the end face by irradiating a laser beam to abutment of the end surface, the both side edges in the upstream side in the movement direction of the belt-like metal plate from the abutment of the end face wave by the imaging means a strip metal plate comprising
Length is dimensionally imaged by light exceeding 450 nm, extracts a large number of edge data indicating the edge positions of people the both side edges respectively obtained by imaging, each side edge based on the extracted edge data Me the edge approximation curve which approximates songs <br/> line determined, corresponds to each side edge
That find the intersection edge approximate curve, the irradiation position of the laser light based on the intersection of the data obtained, the production method of welding pipes, characterized in that moving in a direction crossing the moving direction. 2. The method according to claim 1, wherein the edge of the strip-shaped metal plate is 450 nm or less.
The method for manufacturing a welded pipe according to claim 1, wherein imaging is performed by blocking light having a lower wavelength. 3. A belt-shaped metal plate is moved in its length direction.
Then, the band-shaped metal plate is opposed at both side edges in the width direction.
Curved into an open pipe shape,
Preheated by high-frequency heating, and the preheated end faces
And irradiate a laser beam to the abutting part on the end face to
In the apparatus for manufacturing a welded pipe for welding a portion, the upstream end in the moving direction of the band-shaped metal plate from the abutting portion on the end surface.
Wavelength exceeds 450 nm
Imaging means for imaging two-dimensionally with light
The edge position of each side edge is indicated by the image data
Means to extract a large number of edge data, and each extracted edge
Find two edge approximation curves corresponding to the edges,
Means for determining the intersection of the corresponding two edge approximation curves;
The laser beam based on the data of the intersection
Means for moving in a direction intersecting with the direction in which
An apparatus for manufacturing welded pipes, comprising: 4. An edge of said strip-shaped metal plate and said imaging means
Optics that do not transmit light with a wavelength of 450 nm or less between
Apparatus for producing a welded tube according to claim 3, wherein the Ru with a filter. 5. The apparatus according to claim 1, wherein said imaging means has a wavelength of 450 nm or less.
4. The apparatus for manufacturing a welded pipe according to claim 3, wherein the apparatus has an optical characteristic of not receiving the light .