JPH1085939A - Arc length control device - Google Patents

Abstract

(57) [Summary] In an arc length control device of a welding device for weaving or oscillating a non-consumable electrode 1 in a groove, unevenness of a base material 4 even during weaving or oscillating at a low frequency. And controlling the arc length sufficiently quickly to stabilize the molten state of the base material 4. In an arc length control device of a welding device for weaving or swinging a non-consumable electrode 1 in a groove, an arc voltage E at an arbitrary position during weaving or swinging.
a is detected, a difference from the reference arc voltage Eg having a set appropriate arc length is calculated, and the welding torch 3 is moved by a distance dD obtained by using the difference voltage dE as a variable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an arc length control device for non-consumable electrode welding, an arc length control device for controlling an arc length during welding, and a non-consumable electrode arc automatic welding equipped with the arc length control device. Related to the device.

[0002]

2. Description of the Related Art In non-consumable electrode welding, it is desirable to perform welding while maintaining a constant distance between the tip of the non-consumable electrode and a base material, which is usually called an arc length. In a conventional non-consumable electrode arc automatic welding apparatus, a welding torch is mounted on a slide base, and by utilizing that the arc voltage changes when the arc length changes, the slide base is driven to keep the arc voltage constant. Has been controlled.

Many of the conventional arc length control devices detect a difference between an arc voltage and a reference arc voltage that is a predetermined appropriate arc length, and raises a slide base having a constant driving speed according to the magnitude relationship. On / off control to lower or stop was performed. Alternatively, proportional control that takes the difference between the arc voltage and a reference arc voltage that provides a predetermined appropriate arc length, changes the moving direction depending on the sign, and increases the drive speed of the slide base in proportion to the absolute value of the voltage difference Had gone. In each case, the arc voltage is always controlled in a feedback manner so as to eliminate the difference voltage.

That is, the difference between the measured arc voltage and a reference arc voltage that is a preset proper arc length is grasped as a distance difference between the current arc length and the proper arc length, and
The concept of moving the welding torch so that the distance difference becomes 0 in each control is not present in the conventional arc length control device.

[0005]

The non-consumable electrode is moved left and right (hereinafter referred to as weaving) or twisted in a groove so as to move the tip of the electrode horizontally (hereinafter referred to as swinging).
In the V groove and the I groove, when the non-consumable electrode is near the groove center and near the groove wall,
The distance between the tip of the non-consumable electrode and the base material, that is, the arc length is different, and the arc voltage changes. In such a case, if the conventional arc length control device is used as it is, it is necessary to operate the slide base at all times in response to weaving or swinging to raise and lower the welding torch, and to operate so that the arc voltage becomes constant. . When such an operation is performed, especially when the electrode approaches the groove wall of the groove I, the arc length becomes extremely short, so that the slide base rises rapidly and the molten state of the base material becomes unstable. In other words, it causes the welding result to deteriorate. In order to prevent such a phenomenon, it is necessary to maintain the height of the welding torch at the center of the groove even when the arc torch deviates from the center of the groove while controlling the arc length at the center of the groove to be constant. Will be needed.

In order to perform such an operation, the arc voltage is detected and controlled separately for the case where the non-consumable electrode tip is near the groove center and the case where it is near the groove wall surface.

When the conventional arc length control device is used to detect only the arc voltage at the center of the groove and perform arc length control, the conventional slide base driving speed is maintained at, for example, 1 to 3 Hz. -In the case of bing or swinging, the slide base moves too much in one direction until the next arc voltage detection is performed, resulting in a hunting state in which the slide base repeatedly moves up and down. Had to be very slow.
However, when the drive speed of the slide base is low, it is often difficult to control the arc length corresponding to the unevenness of the surface of the base material, and the non-consumable electrode contacts and damages the base material, making the molten state of the base material unstable. In other words, it causes deterioration of welding results.

An object of the present invention is to increase the driving speed of the slide base even when weaving or oscillating in a groove at an arbitrary frequency in order to solve the above-mentioned problems of the prior art. An object of the present invention is to provide an arc length control device and a non-consumable electrode arc automatic welding device which can be controlled as they are and control the arc length sufficiently quickly in response to irregularities of the base material.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an arc length control device for a non-consumable electrode arc welding apparatus, in which a non-consumable electrode is arbitrarily set at an arbitrary frequency while weaving or oscillating in a groove. An arc voltage is detected only at a position, a difference voltage from a reference arc voltage having a predetermined appropriate arc length is calculated, a moving direction is determined by the sign of the difference voltage, and the welding torch is used with the difference voltage as a variable. By moving the welding torch up and down with respect to the base material by the distance, the arc length is controlled to be constant.

[0010] The device of the present invention, when weaving or rocking the non-consumable electrode in the groove at an arbitrary frequency,
An arc voltage when the non-consumable electrode is at an arbitrary point in the groove is detected, a difference between the arc voltage and a reference arc voltage that is a preset appropriate arc length is calculated, and a moving direction is determined by the positive or negative of the difference voltage. Further, the slide base is driven by a distance obtained by using the difference voltage as a variable. For this reason, the welding torch can be moved at the same moving speed as the conventional arc length control device even during swinging, weaving and swinging at a low frequency, and the arc length can be controlled sufficiently quickly in response to irregularities of the base material. So
There is no problem that the non-consumable electrode contacts the base material and interrupts welding.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a conceptual diagram showing a case where the non-consumable electrode 1 is welded in an I groove 2 while being weaved.
(1) is a case where the conventional arc length control device is used as it is. Since the non-consumable electrode 1 is operated so that the arc voltage is always constant, the arc length Lw when the electrode approaches the groove wall surface is reduced. It becomes extremely short, and the non-consumable electrode 1 rises rapidly, making the molten state of the base material unstable and causing deterioration of the welding result. In order to prevent such a phenomenon, while controlling the arc length Lc at the center of the groove to be constant,
(2) is to maintain the height of the welding torch at the center of the groove even when it comes off the center of the groove. By performing the control of (2), when the non-consumable electrode 1 approaches the groove wall surface, the non-consumable electrode 1 does not rise rapidly, and the molten state of the base material can be stabilized.

FIG. 2 shows a case where the arc length control is performed by detecting only the arc voltage at the center of the groove by using the conventional arc length control device during welding while weaving, and the arc of the present invention. FIG. 4 is a conceptual diagram of arc length control when a length control device is used. The welding torch moving speed is 5 mm / sec in both cases, the arc voltage sampling frequency is 2 Hz (weaving frequency is 1 Hz), and the welding speed is 1 mm / sec. The height of the groove bottom is 100 mm in the welding progress direction, and the height is reduced by 10 mm as an example. W is a weaving locus of the welding torch, and an arc voltage is detected at an intersection P with C which is the center of the weaving amplitude. The locus of the ideal welding torch height corresponding to the groove bottom height is R, the locus of the welding torch height when the conventional arc length control is performed is S, and when the arc length control of the present invention is performed. The locus of the welding torch height is H.

In the conventional arc length control device, as shown in the figure, the interval of arc voltage detection is too long, causing a hunting state in which the slide base repeatedly moves up and down frequently. On the other hand, if the arc length control device of the present invention is used, the welding torch is lowered at a sufficiently high moving speed only for a distance short of the appropriate arc length at the time of arc voltage detection, so that the groove bottom height does not occur without causing a hunting state. The arc length can be controlled along the line.

The detected arc voltage may be obtained by averaging a plurality of detected arc voltages before and after the intersection P and use the detected arc voltage as the detected arc voltage.

FIG. 3 shows an arc length control using a conventional arc length control device during welding while weaving and detecting only the arc voltage at the center of the groove, and the arc of the present invention. FIG. 4 is a conceptual diagram of arc length control when a length control device is used. The moving speed of the welding torch is set to 0.5 mm / sec in the case of the conventional arc length control device to prevent hunting as shown in FIG. 2, and in the case of the arc length control device of the present invention, the same 5 mm / sec as in FIG. In this example, the arc voltage sampling frequency is 2 Hz (weaving frequency is 1 Hz), and the welding speed is 1 mm / sec. The height of the groove bottom is 100 mm in the welding direction and the height is 100 m
In this example, a sharp change in the groove bottom height that decreases by m is taken as an example. W is a weaving locus of the welding torch, and an arc voltage is detected at an intersection P with C which is the center of the weaving amplitude. The locus of the ideal welding torch height corresponding to the groove bottom height is R, the locus of the welding torch height when the conventional arc length control is performed is J, and when the arc length control of the present invention is performed. The locus of the welding torch height is H.

In the conventional arc length control device, as shown in the figure, the moving speed of the welding torch is too slow, and the arc length control cannot follow the change in the groove bottom height. On the other hand, if the arc length control device of the present invention is used, the welding torch is lowered at a sufficiently high moving speed only at a distance short of the appropriate arc length at the time of arc voltage detection. The arc length can be controlled along the length.

It should be noted that a plurality of detected arc voltages detected before and after the intersection P and averaged may be used as the detected arc voltages.

FIG. 4 shows TI which is one of non-consumable electrode welding.
It is an experimental result which shows the welding current in G (tungsten inert gas) arc welding, the voltage (arc voltage) between the tungsten electrode tip and the base material, and the distance (arc length) between the tungsten electrode tip and the base material.

Although it varies depending on various factors such as the state of the base material, the shielding gas component, the electrode composition and the electrode diameter, and the shape of the electrode tip, there is generally the tendency shown in FIG. That is, in the practical range, (arc length change amount) = (control constant) × (arc voltage change amount).

Therefore, if the difference between the measured arc voltage and the arc voltage that provides an appropriate arc length is “N” V,
The arc length at the time of measurement is “α · N”
mm (α is a control constant), it is interpreted that there is a difference, and by controlling the welding torch to move by “α · N” mm, the arc length is controlled appropriately by the arc length control device of the present invention. is there.

The moving means of the welding torch is only required to be able to control the moving distance, and may be a pulse motor drive by a pulse train command or a servo motor drive having a feedback detector such as an encoder.

FIG. 5 is a flowchart of a control method of the arc length control device according to the present invention. First, a welding torch support moving amount calculation formula dD = α · | dE | (| dE | is dE to calculate a welding torch support moving amount dD necessary for setting the arc length Da at the time of measurement to the appropriate arc length Dg. The absolute value of α
Is a constant). Next, an arc voltage Ea between the tip of the non-consumable electrode during welding and the base material is extracted, and a difference voltage dE between the arc voltage Ea and an arc voltage (reference arc voltage) Eg when an appropriate arc length is maintained is calculated. The calculated difference voltage dE is calculated by using the welding torch support portion moving amount calculation formula dD =
α · | dE | to calculate the welding torch support portion movement amount dD. Next, it is determined whether the difference voltage dE is positive or negative. DE> β
If so, the welding torch support moving axis is lowered by the calculated welding torch moving distance dD. If dE <-β, the welding torch supporting section moving axis is raised by the calculated welding torch supporting moving distance dD. And dE> β, not d
If E <-β is not satisfied (if −β ≦ dE ≦ β), the welding torch support moving shaft is not driven. Thereafter, it is determined whether or not the welding is completed. If the welding is being continued, the control is performed again.

Β is a dead zone for stabilizing control.

FIG. 6 is a block diagram showing a non-consumable electrode arc automatic welding apparatus equipped with the arc length control device of the present invention. The illustrated non-consumable electrode arc automatic welding apparatus sequentially supplies a welding power source 6 for generating an arc 5 between the non-consumable electrode 1 at the tip of the welding torch 3 and the base material 4 and a welding wire 7. Welding wire feeder 8
A welding torch support portion 10 for supporting the welding wire feeding guide 9 and the welding torch 3; and a welding torch support portion moving stage 11 for moving the welding torch support portion 10 up and down to adjust the arc length. Welding torch support moving stage control device 12 for controlling welding torch support moving stage 11, welding torch support moving stage 11
, A weaving stage 13 as a means for weaving to the left and right with respect to the welding progress direction, a weaving stage control device 14 for driving and controlling the weaving stage 13, and a weaving stage position detecting device for extracting position information of the weaving stage 13. 15, a bogie 16 mounted with a welding torch 3, a welding torch support moving section 11, a weaving stage 13, and a welding wire feeding guide 9, and a means for self-propelling in a welding line direction, and an arc voltage Ea from the welding power source 6. , A difference voltage calculator 18 as a means for calculating a difference voltage dE between the arc voltage Ea and a reference arc voltage Eg having an appropriate arc length, and a calculated difference voltage dE. Welding torch that calculates the welding torch support part movement amount dD at which the arc length becomes appropriate A support portion movement amount calculation device 19, the integrated control unit 20 is a unit that performs overall control of each device,
It is comprised including. The welding power source 6, the trolley 16, the welding wire feeding device 8, the welding torch support part moving stage control device 12, the weaving stage control device 14, and the weaving stage position detecting device 15 are integrated control device 2.
0 is synchronously controlled.

In this embodiment, the weaving welding method for moving the non-consumable electrode 1 to the left and right with respect to the welding progress direction is employed. Is also good. In addition, although a computer is used as the general control device 20, a dedicated arithmetic control device or the like may be used. Further, the welding torch 3, the welding torch support moving section 11 and the weaving stage 13
The means for mounting the welding wire feed guide 9 and running in the welding line direction is not limited to the bogie 16 but may be a robot, a manipulator, or the like.

The operation of the apparatus having the above configuration will be described below. First, the carriage 16 is set on the base material 4 to be welded. Next, the overall control device 20 is activated. Activated general control device 2
0 activates the welding power source 6 to generate an arc 5 between the non-consumable electrode 1 at the tip of the welding torch 3 and the base material 4. The overall control device 20 detects that a predetermined time has elapsed since the occurrence of the arc 5, activates the welding wire feeding device 8, and the activated welding wire feeding device 8 starts feeding the welding wire 7. The overall control device 20 detects that a predetermined time has elapsed from the start of the supply of the welding wire 7 and starts running the carriage 16.

The voltage (arc voltage) of the arc 5 generated between the non-consumable electrode 1 and the base material 4 changes when the distance (arc length) between the non-consumable electrode 1 and the base material 4 changes due to irregularities on the surface of the base material 4. Since the electric resistance changes, the electric resistance changes in proportion to the arc length.

When the overall control device 20 receives the position information of the weaving stage 13 from the weaving stage position detecting device 15 and detects that the welding torch 3 is at a predetermined position of the weaving amplitude, the integrated control device 20 sends the information to the arc voltage detecting device 17. The detection of the arc voltage Ea is commanded. The arc voltage detecting device 17 that has received the detection command detects the arc voltage Ea, and the difference voltage calculating device 18 uses the reference arc voltage Eg.
Is calculated. From the calculated difference voltage dE, a welding torch support moving amount dD required to achieve an appropriate arc length is calculated by the welding torch support moving amount calculating device 19. The calculated difference voltage dE and the movement amount d of the welding torch support part
D is sent to the overall control device 20. When the difference voltage dE is positive, the overall control device 20 determines that the arc length is large. When the difference voltage dE is negative, the central control device 20 determines that the arc length is small. In the direction, the welding torch support moving amount dD and a driving command are sent to the welding torch support moving stage controller 12. Upon receiving the drive command, the welding torch support moving stage control device 12 drives the welding torch support moving stage 11.

In this embodiment, the detected arc voltage E
When a is larger than the reference arc voltage Eg, the difference voltage dE is set to be positive, and when it is smaller, the difference voltage dE is set to be negative. good.

The overall control device 20 repeatedly performs the above-described processing until the end of welding, controls the arc length during welding regardless of the unevenness of the surface of the base material 4, and realizes automatic welding.

[0032]

According to the present invention, an arc voltage is detected only at a predetermined position during non-consumable electrode arc welding performed by weaving or swinging a non-consumable electrode within an I groove or a V groove. Calculate the difference voltage from the reference arc voltage that is a preset appropriate arc length, and using the difference voltage as a variable,
The amount of movement of the welding torch is obtained, and by moving the welding torch up and down with respect to the base material by the distance, in particular, 1 to 3 Hz
Even if the groove is weaved or oscillated at a low frequency, the arc length can be set to an appropriate value by a single control in response to the unevenness of the base material. For this reason, in the conventional method, the unstable melting state of the base material due to rapid arc length adjustment near the groove wall surface generated in the I groove or the V groove is eliminated, and the non-consumable electrode contacts the base material. As a result, a problem of interrupting welding does not occur, and a sound welding result can be realized.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram when welding is performed while weaving a non-consumable electrode within an I groove.

FIG. 2 is a conceptual diagram of arc length control of a conventional arc length control device and an arc length control device of the present invention.

FIG. 3 is a conceptual diagram of arc length control of a conventional arc length control device and an arc length control device of the present invention.

FIG. 4 is an experimental result showing a relationship among a welding current, an arc voltage, and an arc length in TIG arc welding.

FIG. 5 is a flowchart of a control method of the arc length control device according to one embodiment of the present invention.

FIG. 6 is a block diagram of a non-consumable electrode arc automatic welding apparatus equipped with an arc length control device according to one embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Non-consumable electrode, 2 ... I groove, 3 ... Welding torch, 4 ... Base material, 5 ... Arc, 7 ... Welding wire, 16 ... Dolly, 17 ...
Arc voltage detecting device, 18: Difference voltage calculating device, 19: Welding torch support part moving amount calculating device, 20: General control device.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazutaka Hosokawa 3-1-1, Sachimachi, Hitachi-shi, Ibaraki Pref. Hitachi, Ltd. Hitachi Plant (72) Koji Hara 3-1-1, Sachimachi, Hitachi-shi, Ibaraki No. 1 Inside Hitachi, Ltd.Hitachi Plant (72) Inventor Takeshi Araya 3-1-1 Sachimachi, Hitachi City, Ibaraki Prefecture Inside Hitachi, Ltd.Hitachi Plant (72) Inventor Kazushi Suzuki Hitachi City, Ibaraki Prefecture 3-1-1, Machi, Hitachi, Ltd.Hitachi Plant (72) Inventor Katsuyoshi Hori 3-36 Takaracho, Kure-shi, Hiroshima Prefecture Babcock Hitachi Kure Research Institute (72) Inventor Toshiaki Takuwa, Kure-shi, Hiroshima No. 6-9, Takara-cho, inside the Kure Factory of Babcock Hitachi Co., Ltd. (72) Nobuo Nakazawa, No. 3-36, Takaracho, Kure-shi, Hiroshima Prefecture

Claims (2)

[Claims] 1. An arc length control device for an arc welding apparatus using a non-consumable electrode, comprising: a welding torch moving means for vertically moving a welding torch holding the non-consumable electrode with respect to a base material (a material to be welded). An arc voltage measuring means for measuring a voltage (arc voltage) between the tip of the non-consumable electrode and the base material; and a reference for determining an arc voltage measured by the arc voltage measuring means and a predetermined appropriate arc length. A difference voltage calculation means for calculating a difference between arc voltages, a movement amount calculation means for calculating a movement amount of the welding torch movement means using the difference voltage calculated by the difference voltage calculation means as a variable, and the welding torch movement means. Drive control means for driving control, the drive control means driving the welding torch moving means up and down based on the movement amount calculated by the movement amount calculation means, and Configuration arc length control apparatus to perform. 2. A non-consumable electrode arc automatic welding apparatus comprising the arc length control device according to claim 1.