JP2632289B2 - Spiral steel pipe automatic welding method - 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 for welding a spiral steel pipe, and more particularly to an improved method for automating the same.

[0002]

2. Description of the Related Art As shown in FIG. 4, in a manufacturing process of a spiral steel pipe, a material (PL) fed in a flat plate shape at the entrance of the process is formed into a tubular shape by a number of rolls at the next stage and formed into a steel pipe. The part (PT) is produced in the left direction in the figure while rotating around the tube axis.

In the above process, a portion bent from a flat plate into a tube and joined to the flat plate portion again is a first welded portion (A), for example, ERW welding (high frequency resistance welding) is performed.
The location where the welding line (= joining line) reaches the top portion of the steel tube by the rotation of the steel tube is defined as a second welded portion (B), where the outer surface is welded. Further, a place where the welding line reaches the ground portion of the pipe by the rotation of the steel pipe is defined as a third welded part, in which inner surface welding is performed.

Since the width of the flat plate material to be fed is not completely constant, the gap at the joint of the first welded portion (A) varies. Since the change in the gap adversely affects the welding, control for keeping the gap constant is indispensable.

[0005] The above control is performed by turning the entire portion formed on the steel pipe around the vicinity of the first welded portion (A) so that the forming angle (the feeding method of the flat plate portion , the formed steel pipe portion,
( Referred to as the angle formed by a plane perpendicular to the tube axis ) to make the gap interval constant, and this is usually called gap control.

Incidentally, since the welding operation is performed in a steel pipe at the third welded portion, an inner surface welding device (4a) is installed in the steel pipe.
Is set up, but since there is no space for people to enter,
A copying method in which the welding torch (43a) follows the welding line is employed. The above copying method uses T
The operator manually sets the welding torch (43a) while setting the V camera (44a) and watching the video taken by this camera.
The gap control described above is performed.
When the tool is operated, the position of the steel pipe changes, so that the welding line is intentionally largely changed when viewed from the TV camera side. Therefore, manual welding in such a situation is extremely difficult, and it is impossible to accurately follow a welding line, and automation of welding at this welded portion has been desired.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide an automatic spiral steel pipe welding method capable of producing an excellent spiral steel pipe by assuming the inner surface welding to be an accurate automatic copying. It is.

[0008]

According to the invention of claim 1 of the present application, "a steel sheet fed in a flat shape"
(PL) is bent, the edges are joined together, and the welding is performed while controlling the forming angle (θ) so that the gap at the joint is constant.The outer surface is welded along the joining line, and then the inner surface is welded. A method for manufacturing a spiral steel pipe, in which a reference line (21) is drawn on a flat steel plate (PL) immediately before forming at a position separated from the edge (p) by a certain distance (a), and the inner surface is welded. Occasionally, a welding torch (43) and a TV camera (44) are mounted at a fixed interval and the pipe shaft (P) of a formed spiral steel pipe (PT) is formed.
The reference line (21) is photographed by the TV camera (44) of the inner surface welding means (4) inserted into the steel pipe portion so as to be able to move back and forth along the x), and the image is displayed on the screen from a video signal including the reference line. The position of the reference line at (D ₁ ) is detected, and the inner surface welding means (4) is adjusted so that the detected position (D ₁ ) matches the predetermined reference line position target value (D ₀ ) in the screen. The welding torch (43) moves back and forth so as to follow the joining line, and a reference line position target value (D ₀ ) under a predetermined forming angle (θ) is set to the forming angle of the gap control. And automatically correcting the detected position (D ₁ ) with the corrected reference line position target value (D ₀ a) based on the change (ΔL). You.

In the automatic welding method according to the present invention, the reference line (21) drawn on the flat plate (PL) immediately before forming is a predetermined distance (a) from the edge (p) of the flat plate (PL). Therefore, the shape of the edge is transferred as it is. Preferably, the fixed distance (a) is set based on the distance between the welding torch (43) and the TV camera (44) in the inner surface welding means (4) described later. The reference line (21) is preferably a white line from the viewpoint of easy recognition on the TV screen, but is not particularly limited thereto.

In the automatic welding method according to the present invention, welding other than the inner surface welding in the formed spiral steel pipe (PT), that is, welding for joining the edges of the flat steel plate (PL) and outer welding of the joining line thereof For any of the methods, a method known in the art is used. In the automatic welding method of the present invention,
The inner surface welding has a so-called automatic copying configuration. The automatic profiling is performed, for example, by using a welding torch (43) and a TV camera.
An inner surface welding means (44) which is attached at a constant interval and is inserted into the formed spiral steel pipe (PT) so as to be able to move back and forth along the pipe axis (Px) of the pipe (PT). (4), an inner surface welding means driving unit (6) for moving the inner surface welding means (4) back and forth by a predetermined distance based on an input signal, and a TV screen of a reference line (21) taken by a TV camera (44). , The detected position (D ₁ ) is compared with a predetermined position (D ₀ ) preset in the TV screen, and the inner surface is adjusted so that the detected position (D ₁ ) coincides with the predetermined position. And a control unit (5) for outputting a signal to the welding means driving unit (6).

The inner surface welding means driving section (6) mainly includes a signal processing section (61) having a signal input section and capable of outputting signals in a predetermined order, and an output signal from the signal processing section (61). And a drive mechanism for moving the inner surface welding means (4) by a predetermined distance based on this. This drive mechanism is preferably, for example, a hydraulic servo mechanism, but is not limited to this.

The control unit (5) is, for example, a welding torch (4) at a predetermined position on the inner surface of a steel pipe having a predetermined forming angle.
3) When the reference line (21) is located on the joining line, the position of the reference line on the TV screen is taken as a reference line position target value (D
₀₎ and the sample-and-hold which can be set (52), the reference line position target value to calculate the amount of change of the reference line position target value based on a change of the forming angle at the time of gap control (D ₀₎ and (D ₀₎ Correction Correction means (53), reference line position calculation means (51) for calculating the position (D ₁ ) of the reference line in the TV screen from the video signal including the reference line by an image processing method, and calculation by the calculation means is the position (D ₁₎ the reference line position target value (D ₀₎ or the corrected reference line position target value (D ₀ a) compared to the said inner surface welding means driving unit
And (6) a comparison means (54) for outputting a signal.

With respect to the calculation of the variation input to the correction means ( 53 ), a change in the forming angle is detected as, for example, a change in the position of the frame (3) on which the spiral steel pipe (PT) is mounted, and the detected value is calculated. A correction formula using the forming angle (θ) as a parameter can be devised based on the correction formula, and can be calculated based on the correction formula. For the above-mentioned correction formula, reference is made to the description of the embodiment described later.

[0014]

According to the invention of claim 1 of the present application, at the time of welding the inner surface of the formed spiral steel pipe (PT),
The position (D ₁ ) of the reference line (21) photographed by the V camera (44) is detected on the TV screen, and the detected position (D ₁ ) is
It is compared with a predetermined reference line position target value (D ₀ ) under a predetermined forming angle (θ) in the V screen. Prior to that, the reference line position target value (D ₀ ) is variation based on the change in the correction, the corrected reference line position target value (D ₀ a) to the detection position (D ₁₎ of the inner surface welding means to match (4) is driven and controlled, the welding torch (43) is located on the joining line.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the illustrated embodiments, but the present invention is not limited thereto. Embodiment 1 FIG. 1 is a schematic configuration diagram including an example of an automatic copying apparatus for performing the spiral steel pipe automatic welding method of the present invention, and FIG. 2 is a schematic block diagram of the automatic copying apparatus of FIG. These figures show an automatic copying machine that mainly focuses on the configuration related to inner surface welding.
(1) shows, the portion excluding the configuration relating to the inner surface welding, namely, a feeding device for a flat steel plate, a forming device for forming a steel pipe portion,
The welding device at the first welding portion (A), the welding device at the second welding portion (B), and the like are the same as those in the conventional example, and therefore, illustration or description thereof is omitted.

The automatic copying apparatus (1) is a white line drawing apparatus.
(2), gap control frame (3), inner surface welding machine
(4) It is mainly composed of an automatic copying control section (5) and an inner surface welding machine driving section (6).

The white line drawing device (2) draws a white line (21) on the plate steel plate (PL) immediately before forming, and the edge of the plate steel plate (PL) is formed.
It is configured to draw a white line while keeping a constant interval (a) from (p).

The gap control frame (3)
The formed spiral steel pipe (PT) is inserted into its pipe shaft (P
It is configured to be rotatable about x) and to be able to pivotally support the spiral steel pipe (PT) about a fixed point (P ₀ ) near the first welded portion (A). A position sensor (31) is attached to a predetermined portion of the gap control frame (3), and the position sensor (31) can detect a base displacement amount when the gap control frame (3) turns. . In this embodiment, the “base” is a steel pipe.
Gap control flange in the sense of the base that supports the
Means the frame, and the “base position” means, for example, that the forming angle is θ
The base when the gap control frame
Can be set arbitrarily, such as the position of
The “base displacement” is determined by the position sensor (31).
The amount of deviation from the detected base position, for example, the molding angle θ
Can be represented by the deviation angle φ. The base displacement amount will be described using a mathematical expression described later, but in the present embodiment,
In order to simplify the explanation, the forming angle θ and the deviation angle φ
Are the first and second welding points and the pipe axis of the steel pipe section (PT).
Adopts the angle when projected on a horizontal plane orthogonal to the plane containing
It shall be.

The inner surface welding machine (4) is a spiral steel pipe (PT)
A rod-shaped inner surface welding main material (41) inserted in and supported in a non-contact state with the spiral steel pipe portion (PT), a hydraulic cylinder (42) for reciprocating the inner surface welding main material (41), and A welding torch (43) attached to the tip of the inner surface welding main material (41),
At a predetermined distance from the welding torch (43), the main material (4
It mainly comprises a TV camera (44) attached to 1). Note that a position sensor (45) is also attached to the inner surface welding main material (41).

The automatic copying control unit (5) is provided with the TV camera (4).
4) having a TV screen for receiving the video signal captured in 4),
Image processing means (51) for calculating a white line position in a TV screen from a video signal including a white line, and an arbitrary base position of the gap control frame (3) (for example, when the forming angle = θ)
Sample holding means (52) for setting the position of the white line on the TV screen when the welding torch (43) is positioned on the joining line as the white line position target value (D ₀ ), and the gap control frame (3). Correction means (53) for calculating and correcting a variation amount (△ L) of the white line position target value based on the base displacement amount when the base position is changed by driving;
The white line position (D ₁ ) calculated by the image processing means (51) is compared with the white line position target value (D ₀ a) corrected by the correction means (53), and the difference is output as a “displacement amount”. And comparing means (54). (55) is a manual correction means, and (56) is a manual button.

The amount of variation (△) in the correction means (53)
The calculation method of L) will be described with reference to FIG. Distance (D) between spiral center (P ₀ ) of gap control frame (3) and forming center [= first welding point] (A), spiral pitch (P), center of pivot in gap control frame (3) ( P ₀ ) to the position sensor (3
When the distance (Ls) to 1) is in the relationship shown in the figure, the displacement amount (B _S ) detected by the position sensor (31)
And the displacement amount at the pitch point (B _B ) is obtained as B _B = (P−D) · B _S / Ls. In addition, the pitch point means the following
I do. In other words, it is bent from a flat plate to a tubular
Welded part (A) to be joined with steel pipe manufacturing
The area that reaches the top of the tube while rotating
The second weld to be welded, after which, while rotating further
Again, the third to be welded internally, to the bottom of the pipe
Assuming that the first and third welds are just one pipe,
It is in a positional relationship of rotation and rotation. Therefore, this rotation
The length in the pipe axis direction corresponding to one rotation is called one pitch,
The touch point indicates a point separated by one pitch. Therefore
The pitch point from the first welding point means the third welding point.
And Displacement of spiral steel pipe at pitch point (B
_{P) is, B P = k · B B} ... (k is a proportionality constant. That gap control
Even if the frame is displaced, the steel being manufactured on it
The displacement of the tube is approximately proportional to the displacement of the base
However, the displacement is not exactly the same as that of the base. Obedience
Means the proportional coefficient of the two types of displacement at this time
I have. )It can be expressed as. The displacement (φ) of the forming angle can be expressed as φ = B _P / P. Therefore than ,,, phi = the _{{k · (P-D)} } · B S / {P · Ls}. On the other hand, the function f (φ) representing the position of the white line including the fluctuation accompanying the gap control on the TV screen is as follows.
Is given as First, toe along the pipe axis of the steel pipe section.
There is a movement axis of the center and a movement axis of the detection center.
These axes are offset for mechanical reasons.
The interval between the moving axes of both centers is defined as OC · cos θ.
(Here, OC extends parallel to the tube axis from the detection point of the TV camera.
The distance between the intersection of the extended line and the welding line and the welding point,
θ represents the forming angle at the base position. ) This OC
cos θ is, as a first approximation, from a practical viewpoint, the forming angle
Is constant regardless of the change of. The welding line and the white line are pipes
Exist at a forming angle θ with the plane perpendicular to the axis.
If the line interval is defined as a, the pipe axis direction between the welding point and the detection point
The direction interval X ₀ is represented by X ₀ = a / cos θ−OC * cos θ * tan θ . Here, the molding angle is controlled by the gap
(Θ + φ), the welding point at this time and the inspection
The distance X ₀ ′ in the pipe axis direction from the output point is expressed by the following equation. X ₀ ′ = a / cos (θ + φ) −OC * cos (θ + φ) * tan (θ + φ) Thus, the molding angle is changed by the gap control.
Then, even variation interval X ₀ of the tube axis direction between the detection point and the weld point
Therefore, just following the detection point will make the welding torch
The situation is that the welding point cannot be traced. So the gap
If the molding angle is changed by the control, the original detection
Varying the position of the point in the tube axis direction of detection points and welding points distance X ₀
It is necessary to perform copying at a point where the conversion is corrected.
Therefore, the function f (φ) representing the corrected white line position is f (φ) = X ₀ ′ −X ₀ = a / cos (θ + φ) −a / cos (θ) −OC · cos (θ) ·） tan (Θ + φ) −tan (θ)} . After all, the variation amount (ΔL) of the white line position target value by the gap control is ΔL = f (φ) −f (φ0) where f (φ0) is at the time of sample hold (= forming angle θ).
F) in the case of And an arithmetic expression is given.

The inner welding machine driving section (6) is provided with the comparing means (5).
4) connected to the sequencer (61), an amplifier (62) for amplifying the output from the sequencer (61), and an oil operated to the hydraulic cylinder (42) based on the output from the amplifier (62). The hydraulic valve (63) for adjusting the amount and the data detected by the position sensor (45) attached to the inner surface welding main material (41) are fed back to the sequencer (61) to adjust the driving amount of the hydraulic cylinder (42). And a hydraulic servo mechanism (6A) for adjustment.

The automatic copying apparatus (1) configured as described above.
The operation of will be described. First, before the operation of the gap control frame (3), the frame position is set to the base position (the forming angle at this time = θ), and in this state, the welding torch (43) is positioned on the joining line. In step 44), a white line is photographed, and the sample and hold means (52) of the automatic scanning control unit (1) is operated to process an image signal containing the white line from the TV camera (44) to perform image processing on the TV screen. Calculate the white line position. This calculated value is set as a white line position target value (D ₀ ). Thereafter, the white line detection position (D ₁ ) on the TV screen calculated based on the video signal of the white line position sequentially shot is output to the automatic copying control unit (5) and compared with the white line position target value (D ₀ ). The difference is output to the sequencer (61) of the inner welding machine drive section (6), and the welding torch (43) of the inner welding machine (4) is controlled to follow the joining line via the hydraulic servo mechanism. You.

On the other hand, when the gap control is operated, the position of the frame (3) fluctuates and the forming angle fluctuates.
The set white line position target value (D ₀ ) itself is changed. In this case, first, the correction means (53) of the automatic copying control unit (5) is operated, and the variation amount (△) of the white line position target value (D ₀ ) is obtained.
L) is calculated as described above. Next, the white line position target value is corrected based on the obtained fluctuation amount (ΔL), and the above-described correction is performed so that the white line detection position (D ₁ ) matches the corrected white line position target value (D ₀ a). Similarly, the automatic copying control unit (5) instructs the inner surface welding machine drive unit (6) to operate, whereby the welding torch (43) of the inner surface welding machine (4) can follow the joining line.

The position displacement amount detected by the position sensor (31) provided on the frame (3) is determined by the sequencer (6).
By inputting the feed forward amount in 1),
This is preferable because instantaneous following can be performed.

[0026]

According to the present invention, it is possible to use an automatic copying method with good accuracy for the inner surface welding of a spiral steel pipe, and to efficiently mass-produce an excellent spiral steel pipe. In addition, since the welding process at the time of manufacturing the spiral steel pipe, that is, the first welding, the second welding (outer surface welding) and the third welding (inner surface welding) can all be performed automatically, the welding process can be easily managed without including the manual welding process. Thus, a spiral steel pipe of uniform quality can be manufactured.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an essential part of an example of an automatic copying apparatus for implementing a spiral steel pipe automatic welding method according to the present invention.

FIG. 2 is a schematic block diagram of the automatic copying apparatus of FIG. 1;

FIG. 3 is a relative positional relationship centered on a gap control frame for explaining a method of calculating a correction value based on gap control.

FIG. 4 is a schematic view of a main part for explaining a conventional spiral steel pipe automatic welding method.

[Explanation of symbols]

(1)… Automatic copying machine (2)… White line drawing device (3)… Gap control frame (4)… Inner welding machine (5)… Automatic copying control unit (6)… Inner welding machine drive unit (21)… White line (31)… Position sensor (41)… Main material of inner surface welding (42)… Hydraulic cylinder (43)… Welding torch (44)… TV camera (45)… Position sensor (51)… Image processing means (52)… Sample Holding means (53)… Correction means (54)… Comparing means (61)… Sequencer (62)… Amplifier (63)… Hydraulic valve (PL)… Sheet steel plate (PT)… Spiral steel pipe (Px)… Pipe shaft (p): Edge of flat steel plate

Claims (1)

(57) [Claims] 1. A steel plate fed in a flat plate shape is bent to join the edges together, and welding is performed while controlling a forming angle so that a gap of the joining portion is constant, and an outer surface is formed along the joining line. A method of manufacturing a spiral steel pipe by welding and then welding an inner surface thereof, wherein a reference line is drawn at a predetermined distance from an edge of a flat steel plate immediately before forming, and a welding torch and a TV are used at the time of inner surface welding. A camera is attached at a fixed interval, and the reference line is photographed by the TV camera of the inner surface welding means inserted into the formed steel pipe part so as to be able to move back and forth along the pipe axis of the formed steel pipe part. Detecting the position of the reference line in the screen from the video signal including the reference line, and moving the inner surface welding means back and forth so as to match the detected position with the reference line position target value predetermined in the screen, Welding torch follows joining line The reference line position target value under the predetermined forming angle is corrected based on the change of the forming angle during the gap control, and the detected position matches the corrected reference line position target value. A method for automatically welding spiral steel pipes.