JPS5933075A - Method and apparatus for copying control of welding torch in direction of groove width - Google Patents

Abstract

PURPOSE:To control positionally a welding torch to the center of groove width with very accuracy, by substituting the change of quantity of arc light for the change of position of arc point and detecting the change of quantity of arc light. CONSTITUTION:When a welding torch 3 is moved along the longitudinal direction of a groove 2, an image 5 of groove at the arc point is always projected on a screen 4, and the change of quantity of light is detected by an image sensor 7. If the welding torch 3 moves out of the center of the groove 2, it is grasped at once by the sensor 7 as a change of quantity of electricity. The present position of the torch 3 at the groove 2 is counted and read in a memory. At the same time, it is calculated by a central processing unit and the result of calculation and initial value are compared. If the result of calculation is smaller, the torch 3 is at the center of the groove. If larger, the welding torch 3 is moved by rotating a motor.

Description

[Detailed Description of the Invention] It relates to a method and an apparatus thereof, in particular, it replaces a change in the position of the arc point with a change in the amount of arc light, and by detecting the change in the amount of arc light, the welding torch is placed at the center position of the groove width. The present invention relates to a welding torch welding torch groove width direction scanning control force method and its device, which enables very accurate position control of the welding torch.

Conventional welding torch groove width direction tracing in MHG, md, 'TIG welding, etc. (1) A method of detecting and controlling changes in the welding arc jet due to the influence of both groove walls.

(2) A method in which a displacement detector is provided on the welding torch to detect and control the displacement between the welding torch and both groove wall crystals.

(3) There is a method of attaching and controlling a curtain guard device to the opening of both openings, but it has the following drawbacks.The method of (1) requires welding in order to improve the penetration into the groove wall surface. Although the wire is oscillated, the arc current becomes unstable due to disturbances in this oscillation or changes in the groove width, often resulting in defective tracing.

In method (2), the temperature of the first weld reaches as high as 200 to 300° C. due to preheating, postheating, or welding arc heat, and there is no detector that can withstand the stop heat. For this reason, one possible method would be to use gas (in other words, unmolded gas) and detect and control changes in the flow rate and back pressure of the gas, but gas turbulence would worsen the gas shielding performance. accompanied by. However, the characteristics of this detector change depending on the width of the groove and the amount of clearance between the groove wall and the detector.

Method (3) cannot control the amount at the arc point.

None of these conventional methods were able to accurately trace in the width direction, but it was difficult for welders to monitor and manually operate the arc point, especially when welding narrow gaps. In order to put into practical use the T-method, which cannot be achieved by controlling only the longitudinal profile of the welding joint, the development of a method of controlling the open profile of the 1-chip welding joint is desperately needed.

The present invention has been made in view of such circumstances, and is not affected by changes in groove width or welding heat.
Control the arc points! The object of the present invention is to provide a method and apparatus for controlling the width direction of a groove in a welded groove, which is simple and capable of controlling the width direction of a groove with extremely high precision. By developing this, we will realize the automation of red-spray welding, thereby improving processing efficiency, stabilizing the quality of the paper, and achieving the purpose of increasing the strength of paper. , the present invention is constructed as follows. The welding groove surface is photographed on the screen of an arc monitor (projector) in the same manner as in general practice, and the photoelectric conversion elements of two image sensors placed on the screen surface are used to capture the image using arc light. Converts the brightness of the groove image in the left and right width directions into a Luz signal. The welding torch is controlled so that the count difference is always constant by counting the number of pulses obtained by this photoelectric conversion and finding the difference in counts between the left and right sides. A preferred embodiment of the present invention, which is configured to correct displacement in the width direction of the groove, will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of an apparatus for carrying out the invention.

As shown in the figure, an arc monitor (projector) 1 of a commonly used welding machine uses arc light from a welding torch 3 inserted into a groove 2 as a light source (see Fig. 2), and a screen 74 2. It is configured to take a picture of the fallen groove image 5 at the arc point. In front of this screen 4, the left and right of the captured groove image 5, that is, the brightness and darkness in the width direction from the left and right base material surface images 6L, 6R with the groove 2 as the center to the center hip of the groove 2, are displayed. Two independent photoelectric conversion circuits 7 are integrated in order to detect each distribution as an electrical signal. This photoelectric conversion circuit 7 is a solid-state image sensor consisting of, for example, a photodiode array and a shift register, and the photodiode corresponding to each point is connected to a shift register to measure the amount of light at each point of the groove images 5L and 5H in the left and right width directions. As shown in Fig. 3, the arc monitor 1, to which the image sensor I is located, detects the moving welds 1-3. The welding torch 3 is integrally connected to the welding torch 3 so that the tyranno 8 or the arc 9 can be constantly monitored from diagonally above at the front in the longitudinal direction of the groove. Therefore, the absolute position of the photographed welding torch image 3a on the screen 4 remains unchanged, and the positional relationship with the image sensor 7 attached to the front surface of the screen 4 also remains unchanged. The welding torch 3 is provided movably in the groove width direction by a drive mechanism 10 comprising a motor (not shown) and a feed screw 10a rotated by the motor. Therefore, due to the rotation of this feed screw 10a. Or due to widthwise displacement of weld 1-3 within the groove,
The groove image 5 on the screen 4 turns orange when it moves from side to side.In order to effectively respond to the large movement of the left and right groove images 5 or the wide and narrow groove width in Metareen 4 soil, the above-mentioned 2. The image sensors 7 take images of welding 1-chi 3aK.
4. It is preferable that the opposing ends be arranged perpendicularly and on a straight line, with opposing ends as close as possible, and the other end long enough to reach the frame 11 of the screen 4.
In addition, 12 in the figure is the weld bead 1, 13 is the groove wall surface, and 1
4 is a wire. FIG. 4 is a block diagram conceptually showing a processing circuit for electrical signals detected by the image sensor 7. As shown in FIG. The clock generator 15 extracts the electrical signal detected by the image sensor 7 as a pulse train, the extracted pulse train is counted by a separately provided counter 20, and the counting output is sent to the control circuit 17 where both pulse trains are counted. The block diagram of FIG. 5 shows the configuration for determining the difference between the counters in more detail. The 6-trundle main unit 15, which is activated by a start signal and stopped by a completion signal, is commonly connected to the 7T5 and 7RK in the image on the right in order to send the same clock. In addition to being able to take out the completion signal from the right image sensor 7R, a dipless amplifier 18R is connected to the output of the image sensor IR in order to increase the detection output of the image sensor IR. The output of the pulse amplifier 18H is connected to the Rn
The R9j' counter 20a, which is connected to the I/R converter 20R, receives a counter dart signal from the converter 21R when the pinnikbold circuit 1'9ffi output is equal to or higher than the slice level set by the controller 21R.・Count the number of zorus, and make Karantake-1
Counting is not performed when there is no signal.

After a certain amount of time has elapsed, the start signal is output. On the other hand, the output of the left image sensor 7r is also output from the pulse amplifier 1 similarly to the right image sensor 7R.
8L is connected to the Lni counter 20+ via the peak hold circuit 19L, and this Ln+ counter 720L is connected to the conglomerate 21 which uses the slice level as a common reference value.
It is controlled by the L counter dart signal. Counted Rni counters 20R and L. The outputs of 1 counter 2OL are both sent to a control circuit 17 such as a central processing unit.
4. The above-mentioned drive mechanism 10 is connected to a control circuit 17 to correct the displacement of the welding torch 3, and when the control circuit signal output is positive, it gives clockwise rotation to the motor and welds 1 to 3.
1. Next, the operation of this device having the above configuration will be described.

First, the welding torch 3 is set at the center position of the groove width.

After setting, the tip 8 or the arrow 9 is focused and a groove image 5 near the arc point is taken at the center of the screen 4 of the arc monitor 1. The subsequent operations are performed according to the flowchart shown in Figure 6.After turning on the device, it is determined whether or not to perform width direction scanning control.
If it is S, all memory built in the control circuit 17 is cleared 1, and then the position of the groove image 5 in the left and right width direction at the arc point when the welding torch 3 is set is determined by the pulse as described later. The count numbers Rn0 and Lno are detected, and the control circuit 11 detects the difference between the count numbers, anO-n.
Find o=Po and find this difference P. The control accuracy Δ is recorded in the memory as an initial value in advance.
Load P0. If the image sensor 7 is installed so that the welding torch 3 takes an image at the center of both image sensors 7, the above initial value Po may be zero.
It is difficult to make the left and right sides completely equal, and it is not always necessary to make them in the center, so a certain integer is generally indicated.

Next, the welding section 1-3 for welding is run in the longitudinal direction of the groove 2. In any case, since the arc motor 1 is integrally connected to the welding torch 3, the groove image 5 at the arc point is always taken at a time of -74, and the change in light is detected by the image sensor 7. ing. now,
Assume that the welding torch 3 is deviated from the center of the groove 2 and is displaced somewhat to the left as shown in FIG. This displacement is immediately captured by the image sensor 7 as a change in the amount of electricity. This trapping is done as follows. In the groove image 5 schematically shown in FIG. 8 when the image sensor 7 has a 5-bit configuration for convenience, at the initial stage or when the welding torch 3 is at the center position of the groove width, the arc 9 is ), it comes to the center of the groove width. The brightness of the groove image is the brightest at the center of the groove width, and the brightness decreases somewhat as you move away from the center, and the arc light does not reach the base material surface 6, so excluding the part facing the groove 2. 1. The photodiodes Q+ of the left and right image sensors 7 located on the surface of the wood are extremely dark.
, Q2, and Qs, when a clock signal enters each bit, a dark current of almost zero flows as shown in FIG. Although a large negative current flows through Q4 and Qs, the brightness and darkness of the left and right sides are symmetrical.

Therefore, in the end, the values from the bit end of the image sensor 7 to the groove wall surface 13 counted by the Rni counter 20R and the Lni counter 20■ are both 3.
The difference is P. (p;)"o.However, as described above, when welding 1-3 moves to the left, the left groove wall 131 approaches the arc 9 as shown in FIG. The photodiode Q3 of the image sensor 7R on the right turns into a dark current.
is switched to a bright current, and the displacement of the welding torch 3 is thus grasped as a change in the amount of electricity.

The amount of electricity is transmitted from the image sensor γ to b1 in FIG. 10 in the order of Q+, Q2, . One row is taken out as shown in b2. The powerful pulse train is amplified by the amplifier 18.
The waveform is shaped into a CI+02 waveform, and the peak hold circuit 19 generates a wide pulse with a high signal-to-noise ratio as shown in dI+d2. Since the counter gate signal el+e2 is output only when the Ln1 counter 201 counts 4 pulses and +
The Rni counter 20R counts two. Pulses nl and nR below the slice level are ignored as noise.

In this way, the current position of the welding torch 3 in the groove 2 is counted and read into the memory, and at the same time, in the central processing unit 17, Rni-Lni=Pi (2-4-12
) is performed. Next, first, the initial value 1pol including the size 1Pil of the obtained calculation result and the precision ΔPo
Comparison with the size of IPil>1Pof+ΔPo If the size lpH of the calculation result is smaller, the welding torch 3 is at the center position of the groove width, so there is no need to correct the position in the width direction and the motor is turned off. However, if it is the opposite, then the sign of the calculation result P1 is determined and the direction of displacement of the welding torch 3 is determined. This is the Rni counter 20a and Ln
By specifying that when calculating the count output difference with the i counter 20L, always subtract one from the other,
This is because the signs of rightward displacement and leftward displacement are opposite. In the above example, since Pi=-2, the direction determination is No.
The motor is rotated counterclockwise to draw the feed screw (right-hand screw) 10a toward the motor as shown in FIG. 7, and the welding torch 3 is moved to the right side groove wall 13R. This movement is performed until the error comparison becomes No because the count of the output of the image sensor 7 described above is performed periodically by repeating the start signal and the completion signal. If the direction determination is positive, the motor is rotated clockwise and the welding torch 3 is moved to the left side groove wall 131 in the same way.
move it to

Furthermore, suppose that the groove width changes from the middle, in this case, the number of bits of the image sensor 7 that functions effectively after the change increases or decreases by the same number on the left and right, so the initial value P
. There are no changes. In addition, since the calculation result Pi of reading the current position of the welding torch 3 is a difference value rather than an absolute value of the number of P pulses, the output of the central processing unit 17 is not affected overall even if the number of pulses increases or decreases. The welding torch 3 can be moved in the width direction as described above.

Therefore, even if the welding torch 3 swings from side to side while traveling, the displacement in the groove width direction is grasped as the relative displacement of the groove image 5 with respect to the welding torch image 3a because the welding torch 3 and the arc monitor 1 are integrated. Displacement is screen 4
It is detected by an image sensor 7 fixed to the groove, and is corrected so that it is always at the center position of the groove width, and its accuracy is improved as much as possible by increasing the number of bits of the image sensor 7.
Furthermore, since the displacement of the welding torch is detected and processed as an electric signal, extremely quick width direction scanning control can be performed. Also, ah? Monitor 1 ← Since the groove image 5 taken out uses arc light as the source, it is possible to accurately control tracing at the arc point, and it is also taken on screen 4 rather than on 4 images due to substitute characteristics such as welding arc current. Since the position of the exposed groove wall surface 13 is directly measured, it is completely unaffected by disturbances in the welding arc current, and extremely stable control is possible. In addition, in the Ω welding machine that oscillates the groove 17, the opening red image varies slightly depending on the direction of arc oscillation, and tracing control is required. Since it means moving, I would rather try to get the final result.

In summary, the present invention exhibits the following excellent effects.

(1) According to this method, the groove width is not affected by changes in groove width or welding heat, and control at the arc point can be performed, and the groove can be opened using the arc light during welding as a light source. Since the image is taken on the second screen, the contrast between light and dark at the groove wall surface becomes extremely clear, making it possible to accurately detect the groove wall surface position. Moreover, by detecting the brightness of the detected groove image as an electric pulse and controlling the relative position of the groove and the welding torch based on the pulse count, the response speed is fast and the opening speed is fast. Extremely accurate groove width direction tracing control can be performed that is not affected by variations in the groove width, and is particularly effective for narrow groove welding.

(2) This device also simplifies the device by simply attaching a photoelectric conversion circuit such as an image sensor to the arc monitor of a commonly used welding machine, with almost no modification required. Moreover, it can be manufactured at a much lower cost than the method of obtaining a groove image using the scanning line of a television monitor. ! ,Ta,
By using two photoelectric conversion circuits such as image sensors, the present invention can be applied to wide grooves.

(3) Automatic welding can be achieved through the development of a welding torch welding torch control device, which will improve welding efficiency, stabilize quality, and significantly save labor.

[Brief explanation of the drawing]

The figures show a preferred embodiment of the groove width direction profiling device according to the present invention, and the first drop is a conceptual diagram of the finished product, and the second figure is a cross-sectional diagram taken along line A-A' in Figure 1. Fig. 3 is a schematic front view of the structure of this device, Fig. 4 is a schematic block circuit diagram of this device, Fig. 5 is a detailed block circuit diagram of this device, Fig. 6 is a flow chart of this device, and Fig. 7 is a welding diagram. Torch displacement and control explanatory diagram,
Fig. 8 is an explanatory diagram showing the electricity quantity distribution in the initial state in the photoelectric conversion element, Fig. 9 is an explanatory diagram showing the electricity quantity distribution in the same displaced state, and Fig. 10 is a timing chart of Fig. 5. In the figure, 1 is an arc monitor, 2 is a groove, 3 is a welding torch, 4 is a screen, 5 is a groove image, γ is a photoelectric conversion circuit such as an image sensor, 9 is an arc, 10 is 5 a drive mechanism, 13
17 is a control circuit, and 20 is a counter. Special applicant: Ishikawajima-Harima Heavy Industries Co., Ltd. Agent: Patent attorney: Nobuo Kinutani

Claims (2)

[Claims] (1) A groove image is taken in the longitudinal direction of the groove using the arc light of the welding torch as the light source on the screen of the arc monitor, and the distribution of brightness and darkness in the left and right width directions of this photographed groove image The positions of the left and right groove images with respect to the welding torch are detected by converting them into electrical signals, and counting the number of P pulses obtained by photoelectric conversion between A method for controlling a welding torch to follow in the width direction of a groove, characterized in that displacement in the width direction of the tip is corrected. (2) An arc monitor that is integrally connected to the traveling welding torch and uses arc light as a light source to take a groove image at the arc point, and the brightness and darkness of the groove image taken by this arc monitor in the left and right width direction. A photoelectric conversion circuit that converts each distribution into a base pulse signal, a counter that counts the pulses of the output of each photoelectric conversion circuit, and a welded to detect the difference between the outputs of both counters and keep this detected value constant! - Welding torch groove width direction scanning characterized by comprising a control circuit that outputs a signal for correcting displacement in the width direction of the welding torch, and a drive mechanism that moves the welding torch in the width direction based on the signal from this control circuit. Control device.