JPS59163081A - Automatic controlling method of penetration welding - Google Patents

Abstract

PURPOSE:To enable automatic control of penetration welding in the stage of welding automatically a groove with a TIG welding machine by controlling the position of an electrode in accordance with the result of comparison with a reference value to maintain a specified arc voltage and controlling at the same time the rate of the wire to be added. CONSTITUTION:Automatic welding of a single Vee groove 2 formed of objects 1, 1' to be welded by TIG welding is accomplished by detecting the arc voltage fluctuating with the change in the root gap (g) of the groove 2 with a detector 21, comparing the arc voltage with a reference arc voltage set in a standard arc voltage setter 22 in a comparator 23, supplying the output therefrom via a servocontrol amplifier 24 to a driving motor 7 to move vertically a welding torch 9 and regulating the height of an electrode 10 attached thereto to control the arc voltage constant. The distance A of the arc from the surface of the objects to be welded is detected at the same instant by a distance detector 12 moving vertically together with the electrode 10 and a wire feeder 13 is controlled in accordance with the detected distance to control the feed rate of the wire to the groove 2, by which the automatic control of penetration welding is accomplished.

Description

[Detailed description of the invention] 4 no The present invention relates to an automatic control method for Uranami welding.

In recent years, pipe welding work has become enormous in the manufacture of motors, ships, etc., and automatic welding has been attempted for quality assurance.

However, conventional means of automation have been limited to simply slowing down the welding torch, mechanizing wire feeding, and highly accurate control of welding current and voltage. Although the rate of variation in the reproducibility of these welding parameters has fallen within 1 to 2%, the larger the diameter of pipe butt welded joints, the more the groove accuracy does not fall within the above range. It has been considered impossible to automate root pass Uranami welding. That is, in conventional automatic welding methods, emphasis is placed on how to keep the standard conditions of welding parameters constant, and control cannot be adapted to changes in the root gap. Therefore, if we try to apply the conventional automatic welding method to Uranami welding as is, in areas where the root gap is too small, there will be insufficient heat input and Uranami will be produced, whereas in areas where the root gap is too large, melt will drop, resulting in In some cases, the product may be defective. For this reason, at present, highly skilled workers visually observe welding phenomena and perform delicate control of conditions to carry out Uranami welding.

The present invention was made in view of the above circumstances, and aims to establish automation of all welding as well as finish welding, which has been automated in the past, and to ensure quality and address the shortage of highly skilled workers in the near future. The purpose of this invention is to provide an automatic control method for Uranami welding.

That is, the automatic control method for uranami welding of the present invention includes an electrode that is disposed on the groove of the workpiece and is movable up and down, and a means that moves up and down together with the electrode to detect the distance to the surface of the workpiece. and a wire feeder that supplies a welding wire near the tip of the electrode in the groove to automatically control uranami welding. The height of the electrode is controlled to keep the arc voltage constant by detecting the varying arc voltage and comparing it with a reference value. The method is characterized in that the distance is detected and the amount of wire added from the wire feeder is controlled based on the comparison with a reference value. explain.

In the figure, 1 and 1' are objects to be welded together (butt joints of pipes), and there is a V between the two objects 1 and 1'.
A groove 2 is formed, and a bead 3 is formed in this groove 2. A rail 4 is flanged along the outer circumferential surface of one of the objects to be welded 1', and a rotary cart 5 is mounted on this rail 4. A vertical slide 6 is disposed above the V-shaped groove 2 of the rotary cart 5. A drive motor 7 is attached to the upper end of the vertical slide 6 to drive a slide movable portion 8 that moves up and down along the vertical slide 6. Nine TIG welding torches are attached to this slide movable part 8, and a tungsten electrode 1o is made to protrude into the V-groove 2 from its tip. Further, a distance detector 12 made of, for example, an electromagnetic sensor is attached to the slide movable portion 8 via an arm 11 so as to be located above the other workpiece 1 .

This distance detector 12 is designed to provide a linear output in proportion to the distance from the object 1 to be welded. Further, a wire feeder 13 is attached to the cart 5, and is configured to feed a welding wire 14 to the vicinity of the tip of the electrode 10 within the V-groove 2.

Note that a power source (not shown) is connected between the welding torch 9 and the object to be welded.

Next, the control section of the TIG welding apparatus will be explained.

21 in the figure is an arc voltage detector, and the welding torch 9
and the workpiece 1 to be welded.

This arc voltage detector 21 is a standard arc voltage setting device 22.
The comparator 23 is connected to the comparator 23. Furthermore, this comparator 24 is connected to the drive motor 7 through 24-karat gold.

On the other hand, 25 in the figure is an output voltage detector, which is connected to 61 and the distance detector 12. This output power detector 25 is connected to a comparison inverting amplifier 27 to which a standard voltage setting device 26 is connected. This comparison inverting amplifier 27 is connected to an adder 29 to which a wire feed speed setting device 28 is connected.

Furthermore, this adder 29 inputs the wire feed 'fl!' via the servo amplifier fao. Connected to U13.

An automatic control method for Uranami welding using the above welding device will be explained.

(1) An appropriate welding current and an appropriate running speed of the trolley 5 are set in advance. Also, set the appropriate arc voltage using the standard arc voltage setting device 2.
2, the appropriate feeding speed of the wire feeder 13 is input into the wire feeding speed setting device 2H. Furthermore, when the standard root gap g is used, the appropriate bead height D1, arc length V, and distance A (constant value) between the tip of the electrode 1θ and the tip of the distance detector 12 are added to form a good Uranami bead. A value c is obtained by subtracting the wall thickness t of the objects to be welded 1, 1' from the total value B (=D+V+A). The value of C is the distance between the distance detector 12 and the surface of the workpiece 1 when a good Uranami bead is formed at the standard root gap g,
A voltage proportional to this distance C is input into the standard voltage setting device 26.

(11) When the start button is pressed, an arc is generated between the electrode 1θ and the objects to be welded 1, 1', and the welding wire 14
As soon as it is added to the arc, the truck 5 starts running.

(River) If the actual arc voltage detected by the arc voltage detector 21 during welding fluctuates with respect to the standard arc voltage set by the standard arc voltage setting device 22, the comparator 2
Is the deviation voltage from 3? It is output to the interlocking motor 7 via the Anzo 24, and this drive motor? The welding torch 9 is moved up and down. As a result, the arc length V is kept constant and the actual arc voltage is corrected to the standard arc voltage.

(IV) If the root gap 7″r fluctuates under these conditions and becomes smaller than the standard, the bead height D will decrease because the amount of wire added is the same, even though penetration will be inhibited and no back waves will be produced. Subsequently, the welding torch 9 is raised by the operation 011) above by the amount that the bead height D has increased, and the height C of the distance detector 12 is accordingly increased, and the output voltage is adjusted. As a result, the variation with respect to the standard voltage set by the standard voltage setting device 26 is inputted from the comparison inverting amplifier 27 to the adder 29 as a deviation voltage, and the output voltage to the wire feeding speed setting device 28 is inputted to the adder 29 as a deviation voltage. If the value is smaller than the appropriate feeding speed set in 9,
The feeding speed of the wire feeder 13 is reduced via the servo amplifier 30. Therefore, the welding heat input works to melt the entire groove of the workpiece, making it easier to generate underwaves.

(1/) Contrary to the above Ov), if the root gap g fluctuates and becomes larger than the standard, the melt will be on the verge of a drop,
The Uranami bead hangs down and the bead height D increases 1
．． Contrary to +IV) above, the welding torch 9 descends, the height C of the distance detector 12 becomes smaller 9, and the output voltage to the output voltage regulator 25 decreases. As a result, the variation with respect to the standard voltage set by the standard voltage setter 26 is
?゛ is input as a deviation voltage to the adder 29, which becomes a value larger than the appropriate feeding speed set by the wire feeding speed setting device 28, and is sent to the wire feeder 1 via the servo amplifier 30.
Increase the total feeding speed of 3. Therefore, the amount of molten metal increases and the molten metal is prevented from dripping.

According to the method of the present invention, the variation in the Uranami bead height D due to the size of the root gap g is detected by the full distance detector 12, and the amount of added wire is adjusted to automatically form a uniform Uranami bead. can do.

In the above embodiment, an electromagnetic sensor is used as the distance detector 12, but the sensor is not limited to this, and any sensor that can obtain a linear output in proportion to the distance from the surface of the workpiece may be used, such as a differential transformer, Optical sensor length, fluid sensor length, etc. can be used.

As described in detail above, according to the automatic control method for uranami bath welding of the present invention, it is possible to control welding conditions by adapting to fluctuations in groove precision, and it is possible to perform uranami welding of the root pass, which has been considered difficult until now. This has the remarkable effect of being able to be automated.

[Brief explanation of the drawing]

The figure is a configuration diagram of a welding device used in an embodiment of the present invention. 1.1'... Workpiece to be welded, 2... V-bevel, 3... Bead, 4... Rail, 5... Rotating trolley, 6... Vertical slide, 7... Drive motor, 8... Slide movable part, 9... TlG11 torch, 10... Tungsten electrode, 11 arm, 12... Distance detector, 21...
Arc voltage detector, 22... standard arc voltage setting device,
23...Comparator, 24.30...Servo amplifier, 2
5... Output voltage regulator, 26... Standard voltage setting device,
27... Comparison inverting amplifier, 28... Wire feed speed setting device, 29... Adder.

Claims (1)

[Claims] A vertically movable electrode disposed on the groove of the workpiece, a means for moving up and down with the electrode to detect the distance to the surface of the workpiece, and a welding wire near the tip of the electrode within the groove. When performing automatic control of Uranami welding using a welding device having a wire feeder that supplies The height of the electrode is controlled so as to keep the arc voltage constant, and the distance to the surface of the workpiece is detected by the distance detection means that moves up and down simultaneously with the electrode, and the distance to the surface of the workpiece is detected based on the comparison with a reference value. An automatic control method for uranami welding that includes controlling the amount of wire added from the wire feeder 0