JPH0237978A - Welding output setter for spiral steel pipe welding device - Google Patents

Abstract

PURPOSE:To obtain stable welding quality by detecting a lap quantity, i.e. the overlap quantity at both side ends of steel plates and automatically setting the welding outputs of the spiral steel pipe welding device in accordance therewith. CONSTITUTION:A 1st prescribed distance, i.e. the distance from the end at a 1st side edge part to a 1st mark L1 of the band-shaped steel plate 36 is designated as A1 and the 2nd prescribed distance, i.e. from the 2nd side edge part of the steel plate 36 to the 2nd mark L2 is designated as A2. The above- mentioned lap quantity is indicated by lambda=A1+A2-D if the distance between the 1st and 2nd marks is designated as D. The lap quantity lambda can, therefore, be determined from the distance D between the marks L1 and L2 detected from the images picked up by ITV cameras 241, 242 of an image pickup means. A defect area rate is lowered and the approximately stable welding quality is obtd. by obtaining the above-mentioned lap quality lambda.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a welding output setting device for setting the welding output of electric resistance welding of a spiral steel pipe welding device.

[Prior Art] A spiral steel pipe welding device is a device that winds a band-shaped steel pipe into a cylindrical shape at a predetermined pitch angle, and welds the abutting portions of the opposite side edges that form a pair. Various methods are used for welding, but electric resistance welding (hereinafter referred to as E
RW) is convenient.

ERW is a method in which high-pressure alternating current is applied with both edges of the SL plate wrapped, and the joint is melted and welded by resistance heat generation.As long as the heat input equivalent is kept at an appropriate value, the defect area rate is low. Almost stable welding quality can be obtained.

(Problem to be Solved by the Invention) By the way, it is known from experiments that the ERWO human heat equivalent is expressed by the following formula.

Q=Eplp-to-v'-J2''-θP, jQ,
λr・・・・・・(1) However, Q: Heat input equivalent Eplp: The amount of overlap between both edges of the steel plate that is in contact with the power supply usually does not have a detection means and is affected by coil walk, camber, etc. It fluctuates. In other words, in order to keep the heat input equivalent Q at an appropriate value, it is necessary to grasp the wrap amount λ, and thereby the supplied power Epl
For this reason, in the past, it was necessary to estimate the lamp amount λ for each spiral steel pipe welding device and to prevent fires during welding.
A skilled operator is required to adjust the power supply voltage EP while monitoring the bead shape, and θ near pex angle = plate thickness λ of the steel plate.

An explanation of each of these parameters will be given later, but among them, transport speed ■, power feeding distance! , the apex angle θ and the plate thickness can be easily set or detected;
Ramp amount λ, that is, melting [Object of the invention] The present invention detects the lap amount λ, that is, the overlap amount of both side edges of the steel plate to be welded, and automatically sets the welding output of the spiral steel pipe welding device based on it. , an object of the present invention is to provide a welding output setting device for a spiral steel pipe welding device.

[Means for Solving the Problems] In order to achieve the above object, in the present invention, a first mark is placed at a position a first predetermined distance from the end of the first side edge of a strip-shaped steel plate, and a first mark is placed on the second side edge of the strip-shaped steel plate. at a position a second predetermined distance from the end of the section.
Marking means for recording marks, respectively; Imaging means for capturing an image including the paired first and second marks by winding the steel plate of the spiral steel pipe welding device; From the image, the first and second marks are recorded. and a detection means for detecting the distance between each mark; and a detection means for detecting the distance between each mark; 1st of
The apparatus further includes a welding output setting means for determining the amount of overlap between the side edge and the second side edge and setting the welding output of the spiral steel pipe welding apparatus based on the amount of overlap.

[Operation] That is, the first predetermined distance, that is, the distance from the end of the first side edge to the first mark is Δ1, and the second predetermined distance, that is, the distance from the end of the second side edge to the 27th mark. Δ
2, and if the distance between the first mark and the second mark, which are paired by winding the steel plate of the spiral steel pipe welding device, is D, then
The amount of ramp, that is, the amount of overlap λ between the first side edge and the second side edge due to the winding of the spiral steel pipe welding device is λ=Δ
1+ΔzD (2) Therefore, the overlap amount λ can be determined from the distance between the marks detected from the image taken by the imaging means. As described above, by determining the overlap amount λ, a substantially stable welding quality with a small defect area ratio can be obtained.

[Example〕 Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a system configuration of a spiral steel pipe welding apparatus embodying the present invention as an example, and FIG. 2 shows an external appearance of a part of its mechanism.

As shown in FIG. 1, this system includes a system controller 1, a wrap amount detection unit 2 connected to a system lotus 11, and a spiral steel pipe welding unit 3.
, display 4, printer 5, floppy disk 6
and an operation board 7, etc.

The system controller 1 controls each of these elements according to instructions from the operation board 7, outputs the processing process and processing results to the display 4 and printer 5, and records them on the floppy disk 6 as necessary. Before explaining the details of each of these parts, in order to facilitate the following explanation,
An overview of the mechanical section will be explained with reference to FIG.

In this, 34 is a forming stand supported by a fixed part, and this pressure roll 35a equipped with a facing pressure roll 35a at the tip is attached to the forming stand 34 together with an outer pressure roll 35b provided on the fixed part opposite thereto. On the other hand, while the steel plate 36 set at the pitch angle φ is being conveyed at a speed 2, both side edges of the steel plate 36 are overlapped and pressurized. Upstream of this overlapping part, a power supply chip 32 supported by a bus bar 37 is provided.
1 and 322 are in contact with each side edge (please understand that FIG. 2 shows a state in which the contact is released for convenience of illustration), ERW is performed at the overlapping part, and the steel plate 36 is It is formed into a cylindrical spiral steel tube.

In addition, as the steel plate 36 is transported, the markers 381 and 382 provided upstream of the forming stand 34 cause the steel plate 36 to
Δ1. A white line is marked at the position of Δ2, and I and L2 are marked.

These marks L, L2 are the ■TV provided downstream of the polymerization part.
Read by cameras 241 and 242.

In this embodiment, these IT
V cameras 241 and 242 are fixedly installed at positions making approximately 90 degrees to the welding point W by ERW with respect to the axis of the spiral steel pipe.

Note that the power feeding distance 2 described above is the distance between the power feeding tip 321 and the welding point W, and the apex angle θ is the angle formed by the power feeding tips 321 and 322 with respect to the welding point W.

Referring again to FIG.

The lamp amount detection unit 2 includes an image processing processor 21,
These include an image memory 22, a switching circuit 23, ITV cameras 241 and 242, a monitor TV 25, and the like. The image processing processor 21 controls these elements and, as will be described later, generates an image (multilevel gradation image) including marks L1 and L2 on the spiral steel pipe (steel plate 36 after welding) captured by the ITV cameras 241 and 242. ), their distances are detected and provided to the system controller 1. In addition, IT'll' cameras 241 and 242
The images captured by the user are always displayed on the monitor TV 25.

The spiral steel pipe welding unit 3 includes an ERW power source 31, a boiler driver 33, and the like. The ERW power supply 31 uses data given from the system controller 1 via the interface 12 to set the power supply voltage Ep and the power supply current Ip.
is set and applied between the power supply chips 321 and 322. The servo driver 33 also includes an outer pressure roll 35b.
A motor M that drives the motor M and a timing generator TG coupled thereto are connected, and the motor M is energized at a constant velocity using data given from the system controller 1 via the interface 12.

Next, the operation of the system controller 1 will be explained with reference to the flowchart shown in FIG.

The system controller 1 is started by turning on the power (not shown), and initializes the input/output board, registers, memory, etc. in step 5lo1 (numbers assigned to steps in the flowchart are the same below 2).

At 5102, the input from the operation board 7 is read, and various parameters such as the target heat input equivalent Q, the constant, the conveying speed V of the steel plate 36, the power supply distance i, the appendix angle θ, and the plate thickness of the steel plate 36 are set. Input processing is performed to set the marking positions Δ and Δ2 of marks L1 and L2 and the amount of overlap λ. The lump amount λ to be set at this time is used as temporary data until the image processing processor 21 gives the mark on the spiral steel pipe and the distance D between the mark and L2 (hereinafter referred to as the distance between marks).

By interactively displaying predetermined messages one after another on the display 4, these parameters are set in response to input from the operation board 7 (manual input is OK), and a loop is set to wait for a start instruction.

When a start instruction is given, the process exits the loop and proceeds to step 3105. At this point, the servo driver 33 is instructed to energize the motor M, etc. to obtain the conveyance speed V of the steel plate 36, the pipe passage is started, and the parameter Q' is calculated. and clears count register CN. However, the parameter Q' is Q = Q, K, vrn, In, θ'-jq
- Old - (3) shall be given by the second.

After this, the loop consisting of steps 3107 to 3112 is repeatedly executed until a stop instruction is given or until an abnormality occurs. This loop is set in three ways: when there is no input of the mark interval from the image processing processor 21, when the input is present and the value is appropriate, and when there is the input and the value is not appropriate.

In the first case, in step 5112, the already held wrap amount λ is used to perform the calculation Q゛・λ to obtain the feed power Eplp, and from this, the feed power Eplp is obtained.
p and the power supply current 1p are calculated, and data indicating these values is output to the ERW power supply 31. In other words, until the mark interval is given by the image processing processor 21, the temporary data set according to the input from the operation board 7 is used, and until the image processing processor 21 updates the mark interval, the latest data is used. Depending on the wrap amount λ, ERW
The power supply voltage Ep and power supply current Ip are controlled.

Furthermore, the fact that the calculation Q' ・λ is obtained by solving the above-mentioned equation (1) for the feeding power EpIp is based on the equation (1).
) and (3) 2.

In the second case, that is, the mark interval given by the image processing processor 21 is within the preset tolerance range Dmin.
If the value is less than or equal to Dmax, in 5109, the calculation Δ1+ΔzD is performed to obtain the wrap amount λ, and after clearing the count register CN, in 5112, the power supply voltage Ep is determined using this wrap amount λ in the same manner as above.
and feeding current IP, and the data showing these values is E.
Output toward the RW power supply 31. In addition, Δ1+Δ, -D
The calculation is the same as the above-mentioned (2) No. 2, and Δ1+Δ2 is indicated by Δ in the flowchart.

In the third case, that is, when the mark interval given by the image processing processor 21 exceeds the above-mentioned allowable range, the count register CN is incremented by 1 in S110, and the value of this count register CN is determined to be abnormal in S110. It is compared with the determination threshold CNmax. At this time, the count register CNO value is equal to the threshold value CNma
If it is less than or equal to and control. However, if the mark interval given by the image processing processor 21 continues to exceed the above-mentioned allowable range, the count register CNO value exceeds the threshold value CNmax. It is also possible to terminate the process by instructing to stop the pipe passage, or to control the molding conditions so that they fall within the allowable range.

Further, when there is a stop instruction, the servo driver is also instructed to stop pipe passage, but in this case, the process is performed in 8114, and then the process returns to 5102.

Finally, the operation of the image processing processor 21 will be explained with reference to the flowchart shown in FIG.

The image processing processor 21 performs processing in parallel with the system controller l. Therefore, like the system controller 1, it is activated by turning on the power (not shown), and initializes input/output ports, internal registers, memory, etc. in step 5201.

When the image memory 22 is cleared at 5202, 52
03, the switching circuit 23 is controlled and the ITV camera 2
The image 1 captured by the ITV camera 241 and the image 2 captured by the ITV camera 242 are respectively written into the image memory 22 pixel by pixel. As mentioned above, the ITV cameras 241 and 242 are installed at a position approximately 90° downstream of the welding point W with respect to the axis of the spiral steel pipe (see Figure 3), and the seam (seamed part by welding) is located at this location. Images of marks L1 and L2 facing each other with the mark L1 and L2 in between are imaged.

Image l and image 2 written to the image memory 22 include
As shown in FIG. 6, separate coordinate systems x-y or +, + are set, but the X-axis and the X'-axis coincide on a straight line parallel to the axis of the spiral steel pipe.

5204 indicates straight line detection processing performed on image 1. This processing includes noise removal processing, edge enhancement, and
It consists of value processing, candidate point extraction processing, histogram creation processing, and linear equation calculation processing.

In the noise removal process, image 1 (multilevel gradation image) is smoothed to remove noise such as individual points. Specifically, the area of image 1 is scanned by rask, and the gradations of the pixel of interest and its 8 neighboring pixels are averaged and replaced with the gradation of the pixel of interest.

In the edge enhancement process, a 3×3 pixel Laplacian filter is used. This filter is a filter that calculates the second-order differential of the image, and as a result, parts of the smoothed image 1 where the gradation changes rapidly are replaced with large values, and parts with little gradation changes are replaced with small values. Replaced. Therefore, by binarizing it using an appropriate threshold,
Only the portion where the gradation changes rapidly, that is, the outline of the white line mark 1, is extracted.

In the candidate point extraction process, the image l is scanned by a rask, and the coordinates of points determined to have components by the binarization process are collected.

In this case, the backward scanning pitch is set to 5 pixels, and the candidate point is the one with the largest X mark at the same X coordinate.

In the histogram creation process, a linear equation (-formula) passing through two adjacent points in the X-coordinate direction is found, and a histogram of its coefficients and constants is created.

In the linear equation calculation process, the most frequently occurring coefficients and constants are determined from the histogram of coefficients and constants, and a straight line (hereinafter referred to as an approximate straight line) 2f1 that is marked and describes 1 is calculated based on the coefficients and constants that appear most frequently.

In step 5205, similarly to step 5204, straight line detection processing is performed on image 2, and the approximate linear equation f of marks I and 2 is calculated.
Calculate 2.

Note that in this example, for convenience of processing, the linear equation f,
and f2 are determined as a function of y.

At 3206, the coefficients of the linear equations "1" and "r2" are compared. At this time, if they are within a range that can be considered parallel, it is determined that they are compatible and the process proceeds to 5207, but if not, the process returns to 5202.

In 5207, the mark L at the predetermined X coordinate,
The distance D1 from the approximate straight line to the right edge of image 1, and
The distance D2 from the approximate straight line of the mark 2 at the predetermined y' coordinate to the left edge of the image 2 is determined, the mark interval is calculated, and the result is output to the system controller 1.

Please refer again to FIG. 6 in this regard.

Since the X coordinate set for image 1 and the X coordinate set for image 2 match, the points on each approximate straight line indicated by these exist on a straight line parallel to the axis of the spiral steel pipe. In other words, if we find the interval D' between these points, using the inclination angle φ of the approximate straight line, the mark interval is: D=D''sinφ...
It is given by (4).

In No. (4) 2, the distance D” between the points is the distance above,
, D2 and the distance between the right edge of image 1 and the left edge of image 2. However, the distances D1 and D2 are the linear equations f1 and f2 plus a predetermined value of the X coordinate (in this example, 0
It is determined from the X coordinate of each point obtained by substituting
Distance. is fixedly given due to the installation relationship of ITV cameras 241 and 242. In addition, in this example,
The inclination angle φ of the approximate straight line is the average value of the inclination angles of each approximate straight line.

In the image processor 21, the above 5201 to 52
07 is repeatedly executed.

〔Effect of the invention〕

FIGS. 7a and 7b are graphs comparing the wrap amount λ calculated at that time and the wrap amount λr actually measured using a caliper with respect to the length in the seam direction when the present invention was implemented on an actual machine. Moreover, FIG. 7C is a graph obtained by performing similar measurements on more samples and determining the correlation between the calculated amount of wrap λ and the actually measured amount of wrap λr. Referring to these, it can be seen that the calculated wrap amount λ and the measured wrap amount λr correspond extremely well. Although these graphs do not take into account the deviation between the calculated position of the wrap amount λ and the actual measured position of the wrap amount λr, if it is added, the correspondence between the two will become more reliable.

Figure 8 shows the defect area ratio that appeared in the spiral steel pipe when the spiral steel pipe was created using an actual machine implementing the present invention.
Actual power supply EpIpr and calculated power supply Epl at the time of creation
p, calculated power supply Eplp, measured power supply 1Ep
It is a multidimensional graph showing lp r, calculated power supply voltage Ep, measured power supply voltage Epr, calculated wrap amount λ, and measured wrap amount λr with respect to the length in the seam direction. In this case, when the length in the seam direction was between 0 and 3.5 (m), a skilled operator made adjustments as before, and then switched to the automatic control mode according to the present invention.

Referring to FIG. 8, after switching to automatic control mode,
It can be seen that the defect area ratio has decreased significantly and is stable. This value is suppressed to 1% or less at maximum, indicating that the effect of the present invention is significant.

It should be noted that the image processing shown in the above embodiment is an example and does not limit the present invention.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the system configuration of a spiral steel pipe welding apparatus embodying the present invention as an example, and FIG. 2 is a perspective view showing the external appearance of a part of the mechanism. FIG. 3 shows the ITV cameras 241 and 24 shown in FIG.
2 and a side view showing the installation positions of power supply chips 321 and 322. FIG. FIG. 4 is a flowchart showing the operation of the system controller 1 shown in FIG. 1, and FIG. 5 is a flowchart showing the operation of the image processing processor 21 shown in FIG. FIG. 6 is an explanatory diagram for explaining the principle of detecting mark intervals. FIGS. 7a, 7b, 7c, and 8 are graphs showing the effects of the present invention. 1 Ni-system controller (welding output setting means) 11 Ni-system bus 12: Interface 2 Nilub amount detection unit 21: Image processing processor (detection means) 22: Image memory 23: Switching circuit 24L 242: ITV camera (imaging means) 2
5: Monitor TV 3: Spiral steel pipe welding unit 31: ERW power supply 321, 322: Power supply chip 33: Servo driver 34: Forming stand 35a, 35b: Pressure roll 36: Steel strip 37: Forcer 38L
382: Marker (marking means) 4: Display 5 Nibrintaro: Floppy disk 7: Operation board Applicant: Nippon Steel Corporation Representative Patent Attorney Minoru Aoyagi Figure 1 Figure 2 Figure 4 Figure 5 @ Calculated lap amount λ (mrn) Lap arm λ・λrLmrnl Lap darkness λ・2rfmrnl

Claims (1)

[Claims] 1. Strip-shaped steel plate; A first mark is placed at a position a first predetermined distance from the end of the first side edge of the steel plate, and a second predetermined distance from the end of the second side edge of the steel plate. marking means for recording a second mark on each; imaging means for capturing an image including the paired first and second marks by winding the steel plate of the spiral steel pipe welding device; detection means for detecting the first and second marks and the distance between each mark; and, from the first and second predetermined distances and the distance between each mark, a welding output setting means for determining the amount of overlap between the first side edge and the second side edge of the steel plate due to winding, and setting the welding output of the spiral steel pipe welding device based on the amount of overlap; Welding output setting device for steel pipe welding equipment.