JPS63230275A - Method for controlling interval between torch and base metal for circumferential welding equipment - Google Patents

Abstract

PURPOSE:To constantly secure the weld quality by calculating the quantity of displacement of a torch from the quantity of deviation and the quantity of correction with respect to a reference point between a detector and base metal to move a slider according to the quantity of displacement and maintaining the proper extension. CONSTITUTION:The detector S detects the variation of the circumferential diameter of a work W and outputs a variation=the quantity of deviation from the reference point to an amplifier and sends it out to a computing element. A relative position detector detects the quantity of displacement according to a clearance from the reference position and outputs it to a calculation circuit and calculates the quantity of correction therewith and outputs the quantity of correction for the profiling reference to the computing element. The computing element outputs the quantity of deviation of the present position of the torch T with respect to the proper extension to a comparator and when the quantity of deviation is large, a signal to start a motor is produced to a motor driving circuit and when the quantity of deviation is small, a signal to stop the motor is produced. Then, the slider 2 is slid upward or downward and further, the driving of the motor is stopped. By this method, the extension is maintained constant according to the change of curvature without interrupting the welding.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention is suitable for arc welding the circumference of pipes, pressure vessels, etc., especially when welding the circumference of an elliptical object whose curvature changes, multilayer welding, etc. The present invention relates to a method for controlling the distance between a torch and a base metal in a circumferential welding device suitable for

(Prior Art) In order to maintain constant welding quality, it is necessary to maintain the distance between the electrode tip of the torch T and the base metal (ie, the extension) appropriately, and to maintain the welding voltage and current constant. Conventionally, when welding the circumference of pipes, pressure vessels, etc., the spacing between extensions was adjusted based on signals detected and output by detectors that precede or follow the welding torch. The conventional basic spacing adjustment method is shown in Figure 3 (
Explanation will be made according to a) and (b).

In FIG. 3(a), T is a torch, S is a detector preceding the torch T, Wl is a workpiece with radius R1, Exl
is the extension, 1 is the distance from the predetermined reference point detected by the detector S to the base material, and d is the predetermined interval between the torch T and the detector S.

When welding the circular workpiece W1 with the radius R1, for example, when the detector S detects the distance 'i41 from the reference point set in the detector S to the detection point S, the extension Exl is the appropriate extension Ex. If so, then the radius R2 (for example, R
1<R, 2), when the detector S detects the distance i#T, the torch T is at the position shown by the broken line and takes an inappropriate extension Ex2, so The torch T is manually moved (in this case, forward) to the position indicated by the solid line, and the interval is adjusted so that the appropriate extension Ex=Exl.

(Problems with the prior art) By the way, the conventional spacing adjustment method requires a lot of work each time the radius changes if only circular workpieces with a predetermined radius such as Wl or W2, that is, a constant curvature, are to be welded. If the intervals are adjusted in advance, no problems will occur.

However, when the workpiece W is elliptical or multi-layered, the curvature changes, so continuous welding is not possible, and it is necessary to interrupt welding and adjust the torch spacing. there were. That is, since the distance d between the torch T and the detector S is constant as described above, when the curvature of the workpiece W changes during welding, the difference between before and after the curvature change is as shown in Fig. 3 (a).
) and (b), there is a radial deviation H between the arc point A and the detection point S, as shown as Hl and H2, respectively.
will occur.

For example, from an arc of R1=100Km, R2=50Q m
When moving to an arc of +s, the radial deviation Hl-H2 between the two is calculated as 10 with d = 30 +u.
It is clear that it reaches the dragon as well, resulting in an extension ExO difference (Ex2 - Exl),
If left as is, welding quality in the circumferential direction could not be maintained constant, but welding would have to be interrupted to adjust the interval.

(Object of the Invention) The present invention was made to solve the above-mentioned problems in the conventional method of adjusting the distance between the torch and the base material in circumferential welding equipment. Not only when welding, but also for a workpiece having a circumference with a changing curvature, it is possible to continue welding and automatically maintain an appropriate extension Ex by following the change in curvature, The object of the present invention is to provide a method for controlling the distance between a torch and a base metal in a circumferential welding device that can guarantee constant welding quality at all times.

(Structure of the Invention) The structure of the present invention is as follows. In the case of welding the circumference by making adjustments, (2) the torch and the detector are mounted together on a slider that is attached to the welding machine body and is slidable in a direction substantially perpendicular to the welding surface; , (3) Provide a relative position detector that can detect the relative position between the slider and the welding machine body, and (4) Derive the circumferential diameter or arc diameter of the workpiece from the output signal of the relative position detector and calculate the diameter. (5) On the other hand, it is set to calculate the amount of deviation of the distance between the detector and the base material from the reference point based on the output signal of the detector, and (6) The torch displacement amount that can maintain the appropriate distance between the torch and the base metal is calculated from the deviation amount and the correction amount, and (7) the slider is moved in accordance with the displacement amount. There is a method for controlling the distance between the torch and the base metal in a circumferential welding device.

In other words, the inventor believes that even if the curvature of the workpiece W changes during welding, as long as the radial deviation H between the arc point A and the detection point S does not change, the extension Ex will not change. This is a control method that paradoxically concludes that the extension Ex is maintained constant, and automatically moves the torch T in order to always maintain an appropriate extension Ex according to the diameter of the workpiece W.

In order to achieve this, a detector that moves together with the torch relative to the welding machine body constantly detects changes in the curvature of the workpiece W as the deviation amount H from the reference point to obtain a signal output y. The relative position detector constantly detects the amount of displacement X by which the torch and the detector have moved relative to the welding device body from the reference position, and derives the diameter of the workpiece W from the amount of displacement X. Therefore, if the diameter of the workpiece W is known, the deviation iH can be calculated in advance from a formula according to the diameter of the workpiece W.
It becomes possible to calculate the standard correction amount E for obtaining the appropriate extension Ex. Therefore, for example, if the signal output y±O (deviation from the reference point H-
0) and the displacement lx±0, the correction amount E=O, and as shown by the standard correction amount relationship straight line LE calculated from the calculation formula, ○ If the signal output yo 1 is obtained, the displacement amount
If Qα is shown, then ○Conversely, to obtain the displacement xo1,
If the signal output yoβ is obtained when the displacement amount x02 is indicated, the torch is moved to obtain the signal output yo2 and the reference correction amount relationship straight line 1. This makes it converge on E.

Of course, depending on the settings of the reference point and the reference position, the reference correction amount relationship straight line will slide in the vertical axis direction or the horizontal axis direction, as shown, for example, by the dash-dotted line ME or the dash-double line NE in FIG.

(Function of the Invention) The present invention has a function of controlling the torch to always maintain an appropriate extension Ex even if the diameter of the base material to be welded changes or even if the curvature of the circumference or arc diameter changes during welding. demonstrate.

(Embodiment) The present invention will be described in detail below according to the overall configuration and control circuit configuration of the embodiment shown in FIGS. 2(a) and 2(b), respectively.

In Fig. 2(a), W is a workpiece with an elliptical circumference;
IO is a circumferential welding device according to an embodiment of the present invention, and l is a main body of the circumferential welding device.

Reference numeral 2 denotes a slider attached to the main body 1, which can be slid in the vertical direction along the front surface of the main body 1 in the figure, for example, when a rotary shaft 21 whose axis is in the vertical direction is rotationally driven by a motor 22. An arm portion 2 of the slider 2 extending to the right in the drawing
The tip of No. 3 hangs down, and the lower end is a torch T. The work W is arranged below the torch T at a predetermined interval, and is rotatable, for example, in the direction of the arrow. A wire reel 3 is mounted on the upper part of the arm portion 23, and the welding wire 4 wound around the wire reel 3 is guided to the torch T, so that the rotating workpiece W is The circumference can be welded by an arc generated between the torch T and the base metal.

Reference numeral 51 denotes a copying rod, which is attached to the main body 1 at a predetermined position in the longitudinal direction.
A pin connection 0 is attached to the other end of the support arm 52, which has one end fixed to the
The stretched tip on the right side of the figure is the workpiece W.
The tip portion on the left side is pin-coupled P to the tip of a detector 531 of a scanning sensor made of, for example, a differential transformer, shown as 53. The profiling bar 51, the support arm 52, and the profiling sensor 53 constitute a detector S, and changes in the diameter of the workpiece W rotating in the direction of the arrow move the tip of the profiling bar 51 that contacts the front periphery of the welding point A up and down. The vertical movement is transmitted to the detector 531 of the copying sensor 53 via the pin connection O of the support arm 52,
The copying sensor 53 can detect a change in the diameter of the workpiece W as a deviation amount H from a preset reference point.

Further, reference numeral 6 denotes a relative position detector consisting of, for example, an absolute encoder, which can detect the amount of displacement x of how far the slider 2 is vertically away from a preset reference position. Since it is possible to derive the circumferential diameter of the workpiece W based on the distance relationship between the main body 1 fixed by and the rotation center of the workpiece W, it is also a diameter detector.

The embodiment circumferential welding device 10 having the above configuration is shown in FIG.
) is controlled according to the control circuit flowchart shown in ().

S, 6 and 22 in FIG. 2(b) correspond to the detector S, relative position detector 6 and motor 22 in FIG. 1(a), respectively.

The detector S detects minute fluctuations in the circumference of the workpiece W,
Output the variation value from the reference point minus the deviation amount H to the amplifier 11,
The amplifier 11 amplifies this and outputs it as a signal y to the arithmetic unit 12.
Send to.

The relative position detector 6 detects the displacement amount X according to the separation distance from the reference position, and the calculation circuit 13 calculates the copying reference correction IE by using the value derived from the displacement amount X as the circumferential diameter detection value of the workpiece W. Output to. The calculation circuit 13 stores in advance the copying reference correction amount E based on the diameter, and the copying reference correction amount E calculated according to the input circumferential diameter detection value is sent to the signal yo.
It is output to the arithmetic unit 12 as

The arithmetic unit 12 compares and calculates the signal output y and the signal yo, and calculates the amount of deviation ε (ε
=y-yo) is output A to the comparator 14. The comparator 14 instructs the motor drive circuit 18 to start the motor when the deviation amount ε becomes large . A signal is generated in the ON signal generator 16 to cause the deviation amount ε to be small.
...... 1ε-εo 1<0, the OFF signal generator 16 generates a signal to the motor drive circuit 18 to stop the motor, and the motor drive circuit 18 to which the ON and OFF signals are input receives the ON signal. In response, the motor 22 is driven to rotate the rotary shaft 21 shown in FIG. Motor 22
Stops driving.

In this way, the present invention always controls the distance between the torch T and the base metal as described above, so even when welding a workpiece W whose curvature changes, the torch can be adjusted according to the change in curvature without interrupting welding. T automatically moves to keep the extension Ex constant.

(Other Examples) In the above example, the case where the curvature changes during welding was explained, but in the case of multi-layer welding, the curvature changes every time the welding position goes around, so this can be detected. The torch T automatically moves to maintain the appropriate extension Ex as in the embodiment.

Also, when welding workpieces W with different circumferential diameters one after another, as long as the detector S contacts the workpieces W before starting welding for each workpiece W, the appropriate extension E is applied as in the embodiment.
Of course, the torch T moves automatically to maintain x.

In the above embodiment, the vertical movement of the copying rod 51 is detected by the differential transformer 53 as the detector S, but a non-contact type detector such as an optical or electromagnetic type may also be used. It is not a matter of type. However, copying rod 51
It is convenient to use multilayer stacking with a narrow gap or when the base material is preheated.

Furthermore, although the case has been described in which an absolute encoder is used as the relative position detector 6, it is of course possible to obtain the same effect by using a ground detection means such as Magnescale.

(Effects of the Invention) By implementing the present invention, it is possible to weld not only workpieces with different diameters on the circumference sequentially, but also workpieces with a change in curvature in accordance with the change in curvature without interrupting welding. Since the torch is automatically moved and welding is performed while maintaining the appropriate extension Ex, constant welding quality is guaranteed and complete automation of the circumferential welding machine is achieved, which has an extremely significant effect.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a straight line related to the reference correction amount E for calculating the moving amount of the torch in the present invention, and FIGS. 2(a) and (b) are a front view of the overall configuration of the present invention and a control circuit, respectively. The block diagram and FIGS. 3(a) and 3(b) are partial front views for explaining the conventional method for adjusting the distance between the torch and the base material, respectively. 10------One circumference welding machine 1---Welding machine main body 2---------Slider 6------Relative position detector S---・・・−・−Detector T−・−・・−・・−Torch w−・−・−Base material−Workpiece

Claims (1)

[Claims] When welding the circumference in such a way that the distance between the torch and the base metal is adjusted by the signal that a detector that precedes or follows the welding torch detects the distance between the detector and the base metal and outputs. The torch and the detector are mounted together on a slider that is attached to the welding machine body and is slidable in a direction substantially perpendicular to the welding surface, and a relative position between the slider and the welding machine body can be detected. A position detector is provided, and the circumferential diameter or arc diameter of the workpiece is derived from the output signal of the relative position detector, and a correction amount according to the diameter is calculated.On the other hand, the output signal of the detector is Set to find the amount of deviation of the distance between the detector and the base material from the reference point,
A circle characterized in that the amount of displacement of the torch that can maintain the distance between the torch and the base material at an appropriate distance is calculated from the amount of deviation and the amount of correction, and the slider is moved in accordance with the amount of displacement. A method for controlling the distance between the torch and base metal in circumferential welding equipment.