JPS62267071A - Control method for one side welding - Google Patents

Abstract

PURPOSE:To enable a good back bead shape and the uniformity of the front bead with one side welding by finding the welding speed with the input of various welding conditions to an arithmetic unit with controlling an electrode by its movement in the axial direction of the welding electrode and in the width direction of a groove and performing the welding at this speed. CONSTITUTION:A welding electrode 5 is reciprocally rocked in the width direction (X axis) of the inside of a groove 2 and simultaneously moved in the height direction (Y axis) so that the arc length becomes constant. This respective movement is controlled by moving mechanisms 4X, 4Y. The moving width of one cycle of the electrode 5 is detected by a displacement gage 6X and the height of the front bead, a wire speed, groove angle, etc. are inputted into an arithmetic unit 20 together with this detection value. The welding speed is operated from this result and the welding is performed with this welding speed as that of the succeeding cycle. In this way, a stabilized one side welding is enabled, a good back bead is always held and the bead having uniform height of the front bead can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a control method for single-sided welding.

[Conventional technology]

FIG. 4 is a configuration diagram showing a conventional welding device.

A welding cart (3) that is movable along the groove (2) with respect to the base material (1) to be welded has a welding electrode (5) in the height direction (Y-axis) and groove width direction (X-axis). Both transfers with axis)! gI1 mechanism (
4Y) and (4x). The welding Ti
The pole (5) moves in the direction of the groove line while oscillating in the width direction within the groove, and at the same time its movement in the Y-axis direction is controlled to keep the arc length constant, and its displacement is determined by the displacement of a potentiometer, etc. Detected in total (6Y). In addition, the above electrode (
The displacement in the X-axis direction during the rocking in the groove width direction in step 5) is also detected by a displacement meter (6x) such as a potentiometer. Electrode (5) of consumable or non-consumable electrode and base material (
A welding power source (7) is connected between the welding power source 1) and a constant current power source or a constant voltage power source depending on the welding purpose. Note that (8) is an arc voltage detector, and (9) is an arc current detector, which are provided as necessary for control.

The basis of the control method is the electric AI T51 groove (2
) in the radial direction (X-axis), and at the same time move the electrode (5) in the height direction (Y-axis) so that the aperture length is always constant.
This is constant arc length controlled swing welding performed while moving the electrode (5), and the swing of the electrode (5) in the X-axis direction is caused by the
Q
The movement control in the Y-axis direction is performed by a moving machine* (4Y) driven by a Y-axis moke (IOY). In the illustrated example, the moving mechanism (4x) that supports the electrode (5) movably in the X-axis direction is supported by the moving ff1h'l (4'l') so that it can also move in the Y-axis direction, Furthermore, the moving mechanism (4Y) is supported by a trolley (31).

Figure 5 is a basic circuit configuration diagram of constant arc length control using the Y-axis motor (IOY). If the power source (7) is a constant current power source, the arc voltage from the arc voltage detector (8) is detected, and if the power source (7) is a constant voltage power source, the arc current detector (
The arc current from 9) is input to the differential amplifier αυ, and the difference between it and the reference value set in advance on the setting device is calculated by the amplifier αl.
A drive controller 0318 is provided to drive the Y-axis motor (IOY) at a speed corresponding to this differential output. This circuit keeps the arc voltage (or arc current) constant, the arc length is constant, and the electrode (
5) When moving in the X-axis direction, the electrode tip moves along the groove wall.

Movement of the electrode (g) in the X-axis direction is controlled by a drive control circuit shown in FIG. That is, in the figure, the X-axis motor (IOY) is controlled via the controller to rotate at a constant speed preset by the setting device α4, and further, whenever the controller receives a signal from the switching pulse generator 01. Additionally, the rotation direction of the X-axis motor (IOX) is configured to be reversed. Electricity 8 detected by displacement meter (6Y)
ii (The amount of displacement (ey) in the Y-axis direction of 51 is the end position setting value (e
o) and compared by comparator □□□, (ey)
The switching pulse generator side issues a reverse rotation command signal to the controller (5) in response to a signal output from the comparator (to) every time the rotation angle becomes equal to (eo).

FIG. 7 is an explanatory diagram showing the relationship between the movement of the electrode (5) under the above control and the weld metal. FIG. 7 (al) shows the moving state of the filter electric current ltj+51 by the apparatus shown in FIG. 4, and shows the positional relationship between the filter weld metal and the electrode tip formed in FIG. ) shows the locus of the electrode tip, (1a) is the base material surface, (2a) is the bottom surface of the groove, (3
) is the backing material, and G1 is the weld metal.

Next, the operation will be explained.

In FIG. 7 (λ), first the electrode (5) is placed at the grooved end (
b) and store the Y-axis displacement at this time as eo. When an arc is generated and movement in the X-axis direction is started, the electrode tip moves almost along the groove wall surface as shown in E-Roha in the figure due to the above-mentioned constant arc length, and the electrode tip moves along the trajectory (5a). Give me 1. When the displacement meter (6Y) reaches 8, the output ey of the displacement meter (6Y) becomes eo again, and the direction of movement of the X-axis is reversed by the control circuit operation shown in FIG. 3, and this operation is repeated thereafter.

Here, from one end of the swing (A: C) to the other end (
The period up to (c) and (b) is one cycle of oscillation. According to this control method, no matter how the groove shape changes, or even if the center of the groove deviates from the traveling direction of the welding cart, the tip of the electrode remains constant from the base metal surface or the bottom of the groove. This means that the inversion and oscillation are repeated within the groove width while maintaining the distance of .

[Problem that the invention seeks to solve]

By the way, what can we do to make welding unmanned? It is necessary to automatically detect and correct the welding torch position in response to two-dimensional changes in the groove line that change moment by moment during fI contact. A working welding torch position adjustment 81 groove is required.

Conventionally, detection sensors for this purpose include contact sensors and electromagnetic photoelectric type non-contact sensors, which have been put into practical use.

Furthermore, in a welded joint, there are variations in the shape of the groove width, angle, etc., so it is necessary to detect these variations and automatically control the welding conditions. However, it can be said that there are no useful detection sensors for this purpose, and only a few methods are being considered that use ITV to image the groove in front of the arc and detect the groove width.

However, among the above-mentioned sensors, the former one that detects two-dimensional changes in the groove line should be installed separately from and near welds 1 and -ch, and the detection position and the position of welds 1 and -ch are different from each other. Since a certain interval is required between the two, accurate detection is difficult and there are many practical restrictions such as restrictions on the dimensions of the object.

Furthermore, although the latter ITV method can detect the width of the groove surface, the true groove cross section is unknown, and there is a gap between the detection position and the arc position, so there is a limit to the detection accuracy. However, it has not been put into practical use due to drawbacks such as size restrictions on the objects to which it can be applied.

In view of this situation, the inventors used the welding arc itself, which oscillates within the groove, as a sensor, and were able to accurately position the welding electrode within the groove without using a dedicated sensor separate from the torch. The method of narasero was proposed in Japanese Patent Publication No. 57-3462. This method is useful not only because it allows the welding torch to follow the groove line, but also because the displacement waveform drawn by the torch at that time provides information on the groove cross section directly under the arc.

This invention was made in view of the above circumstances, and detects the welding arc by using the characteristics of the welding arc itself without using a separate sensor to detect the groove position, groove cross-sectional shape, etc. The sensor not only allows the welding torch to follow the bevel line accurately, but also detects the bevel shape and automatically controls the welding conditions, ensuring a good back bead shape even when the bevel condition fluctuates. The object of the present invention is to provide a method for controlling direct welding in which a weld bead with a constant surface bead height is formed.

[Means for solving problems]

The present invention uses a DC or AC constant current characteristic or a DC constant voltage characteristic as a welding power source, and maintains a preset constant arc voltage or welding current in the axial direction of the welding electrode (hereinafter referred to as Y). The distance between the tip of the electrode and the surface of the base material is changed by a moving mechanism (referred to as an axis), thereby controlling the arc length to always be constant. axis), then reverse the direction of the X-axis movement on the condition that the interval distance reaches a preset value, and repeat this operation, thereby adjusting the arc of the electrode end within the groove. In an arc welding device that performs accurate groove tracing while reciprocating in the width direction, and maintains a constant height distance from the base material surface or the bottom of the groove to both ends of the reciprocating movement. , a calculation device is provided, the period from one end of the above-mentioned oscillation to the other end is one cycle, and this one
During a cycle period or an integer multiple thereof, information regarding the width of the oscillation in the X-axis direction, that is, the oscillation width, is detected and stored in the arithmetic unit, and a predetermined wire feeding speed (2) is determined. , the desired front bead height hp, the front bead height hs determined by experiment, etc. are input into the above-mentioned calculation device to calculate the welding speed (■), and the welding speed is calculated during the next cycle of movement or an integral multiple thereof. Welding is carried out with , and this control operation is repeated thereafter.

[Effect]

As a result of welding using the welding speed control method described above, a weld bead can be obtained that simultaneously has a good back bead shape and a front bead having a constant height.

[Embodiments of the invention]

FIG. 1 is a configuration diagram of a welding device showing an embodiment of the present invention.
(A) is an arithmetic unit, and 2D is a motor. As shown in the figure, the movement width WW of one cycle of mS (5) is detected by a displacement meter (6X), and the detected value is input into the arithmetic unit. Front bead height h
p, back bead height ha, g bead penetration width ΔB, wire feeding speed Vf, groove angle θ, and distance ΔW in the X-axis direction between the electrode tip and the groove wall surface at the swinging end. The welding speed (2) is calculated using the formula described below, and this welding speed V is input to the motor et+ to perform welding as the welding speed for the next cycle, and this operation is repeated thereafter.

In addition, h@ in the above specifications is a value that can be determined by experiment, and h
p may take a desired value in advance, and the other values are determined by the welding conditions.

Below, describe the formula for determining the welding speed V from the above specifications. As shown in the welding explanatory diagram of FIG. 7, in one cycle of oscillation, the oscillation rf! detected by the X-axis displacement meter! ! J width (WW) is the groove width (WW) at the swing reversal position (eo point).
B) has the following relationship.

B=WW+2ΔW -, -fil In formula (1), ΔW is the distance between the electrode tip and the groove wall at the swinging end, and is basically a constant determined by the arc length to be set. If the current and arc voltage settings are constant, they will remain constant even if the groove width changes, and this has been confirmed through experiments.

On the other hand, when the back bead shape in single-sided welding using a backing material is in contact with lδ under constant welding conditions, even if the distance gI (root gap) between the workpieces changes at the bottom of the groove, the back bead will be directly below the arc. If molten metal is present in the root gap, the back bead height h6) is almost constant and the back bead width (WW) changes in accordance with the root gap. This has been confirmed through experiments, and Figure 8 shows welding current I = 26OA and welding speed ■
= 16cm/min, MA of wire electrode diameter d = 1.2m+s
This shows an example of experimental results using G welding. From this figure, it can be seen that molten metal exists directly under the arc from route 1 to gap 9, and the back bead height ha is approximately a constant value. Further, the back bead width Wa changes linearly with changes in the root gap. However, when the root gap exceeds 9mm, there is no molten metal directly under the arc, the shape of the back weld becomes thick (changes), and if we try to continue welding, the arc will eventually extinguish and welding will become impossible. The cross-sectional area Aa of the back bead when molten metal exists directly under the arc and stable welding is to be performed can be approximately given by the following equation.

As” −!L ha・W6 Furthermore, since the back bead width W a I is the sum of the root gap G and the penetration width ΔB, Aa −!L hs (G+2ΔB ) −−(31
Here, ΔB is a constant determined by experiment. Therefore, the cross-sectional area A of weld metal 00 is given by: A = ((WW+2ΔW)-2Δbtanθ-hpL) where the distance between the bead surface and the above-mentioned rocking reversal position is Δlx, the front bead height is hp, and the groove angle is θ.
anθlhp+ ′, h s (w, +zΔW)−2
(△h+h p ) tanθ+2ΔB+ --(41 Equation (4) is the groove depth or plate thickness) and the groove angle θ
If the welding conditions are constant and there is no molten metal directly under the arc, then the cross-sectional area A of the weld metal that will always give a good back bead shape and a constant front bead height even under fluctuating groove widths will be , which can be determined by calculation based on the value of the swing width WW detected above.

On the other hand, if the wire feeding speed is 1, the welding speed is 2, and the cross-sectional area of the deposited metal is Δ, then there is the following relationship between them.

Vl=, A-V v(5) V-k・-person However, , is a constant, that is, by inserting the above specifications into the above equation (5), the welding speed V can be determined.

Next, a simpler example of calculating the welding speed will be described. In general, it is not limited to grooves as shown in Fig. 7 (a) and (bl),
Welding conditions such as welding speed, welding current, wire feeding speed, etc. are set in advance as initial values according to the groove shape, and thereafter the above-mentioned welding conditions are changed while checking the fluctuating state of the groove width. According to this method, ■, wire feeding speed as the initial value. , the welding speed is set to vo, and under these conditions, 'f11 welding is started and one cycle of oscillation is performed.The resulting deposited metal is determined to be 81A, which is 80- to 2-! -L-IL ■. −(6) becomes. In addition, the initial swing width WW. shall be. In the next oscillation cycle, the groove width changes, for example, increases and the oscillation width becomes W.
Suppose it becomes W. In this case, in order to ensure a good back bead shape and a constant front bead height hple, the weld cross-sectional area must be increased by ΔA=A−A. That is, in the above equation (4), all parameters except WW are constants, so ΔA=A-A0 (w, -w,.) (h F -+4-h a I-
-f71 Now give the variable h using the following formula.

h = h p +Th e −−1
8] Therefore, a good back bead shape and a constant front bead height h
The welding speed ■ to ensure p is given by the following equations (5) to (8).

y='n=VCoE-A A, + 8 A Using the formula (9), in a groove with fluctuating groove width,
If the desired front bead height hp and front bead height hs are 4 times, the initial welding speed (■) determined before welding. and the wire feeding speed ■I0, and the change in the detected value of the swing width for each cycle, that is, WW-WW. From this, the appropriate welding speed (■) for the next oscillation cycle can be calculated.

FIG. 2 shows a flowchart of the control operation when welding speed is controlled by a microcomputer based on the above formula. In (step 1), first the desired front bead height h
Constant h determined from p and back bead height ha, initial value of welding speed■. , the set value Vc6 of the wire feeding speed is input and stored.

(Step 2) First, A0=V. /V0 is calculated and stored. Welding is started in (step 3). The swing control at this time is based on the mechanism and control circuit shown in FIGS. 4 to 6 described above. When one cycle of oscillation is completed in (step 4), the oscillation width WW0 at that time is detected and memorized in (step 5). Similarly, the next swing cycle is started, and Wl is detected in (step 7) after passing through (step 6).

Conventional welding speed ■. It is. (Step 8)
, -wvo)h is calculated, and in step 9, the welding speed (■) is calculated based on equation (6) regarding the above-mentioned (■).
Starting at step 10, the proper welding speed (2) is performed and the next oscillation cycle begins. Thereafter, after repeating the operations of (step 7) and (step 10), welding is completed in (step 11).

FIG. 3 is a diagram showing the results of implementing the control method according to the present invention. The welding speed ■ is controlled in response to changes in the root gap G, and as a result, it is possible to maintain a state in which the melting metal always exists directly under the arc, resulting in stable welding and the height of the back bead. It can be seen that a weld bead with a constant h8 and a good back bead shape with a back bead width W8 corresponding to the size of the loop 1-gap G and a constant front bead height is formed.

〔Effect of the invention〕

As described above, according to the control method of the present invention, deviations in the groove line and fluctuations in the groove width are detected by using the characteristics of the welding arc itself, without using a separate sensor, and By controlling the welding speed accordingly, welding 1 and - 1 can be accurately aligned with the groove line, and at the same time, stable single-sided welding is possible even when the groove width fluctuates, resulting in consistently good single-sided welding. This has the excellent effect of maintaining the shape of the back bead and making it possible to form a weld bead with a uniform height of the front bead.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of a welding device showing one embodiment of the present invention, Fig. 2 is a flowchart of another embodiment, Fig. 3 is a line diagram showing the effects of the present invention, and Fig. 4 is a conventional welding device. Fig. 5 is a block diagram of constant arc length control, Fig. 6 is a block diagram of the drive control circuit for the X-axis moke of the welding device, Fig. 7 is an explanatory diagram of welding, Fig. 8
The figure is a diagram showing a conventional welding situation. In the figure, (1) is the welding base material, (2) is the groove, (3) is the welding cart, (4X) is the mechanism for moving the electrode in the X-axis direction, (4Y) is the g1 mechanism for moving the electrode in the Y-axis direction, (5 ) is a welding electrode, (6X). (6Y) is a displacement meter, (7) is a power supply, (5) is a calculation device,
211 is a motor. Agent Patent Attorney Masaru Sato Root Cap G (mm) Figure 5 Figure 6 Figure 7

Claims (3)

[Claims] (1) An arc welding method in which the welding electrode is reciprocated in the width direction within the groove, and the welding electrode is moved in the axial direction of the welding electrode, that is, in the Y-axis direction, so as to maintain a preset welding current or arc voltage. The distance between the tip of the electrode and the surface of the base material is changed by a moving mechanism, thereby performing a control operation to keep the arc length constant, while moving the electrode in the width direction of the groove, that is, in the X-axis direction. , the direction of the X-axis movement is reversed when the above-mentioned interval distance reaches a preset value, and by repeating this operation, the arc at the tip of the electrode is reciprocated in the width direction within the groove. In single-sided welding using an arc welding method that performs accurate groove tracing and always maintains a constant height distance from the base metal surface or the bottom of the groove to both ends of the reciprocating swing, the present invention is equipped with a computing device. , the period from one end of the movement to the other end is defined as one cycle, the width W_W of the swing in the X-axis direction during each cycle is detected, and the desired table bead height is detected along with information regarding the width W_W. h_F, back bead height h
_B, back bead penetration width ΔB, wire feeding speed V_f
, the groove angle θ and the distance ΔW in the X-axis direction between the electrode tip and the groove wall surface at the swinging end are input into the above calculation device to calculate the welding speed V, and the next swing is calculated using the welding speed V. 1. A control method for single-sided welding, characterized in that the method is configured to perform one cycle of welding. (2) The information regarding the width W_W is the width W of one cycle.
_W. The single-sided welding control method according to claim 1, wherein: _W. (3) The method for controlling single-sided welding according to claim 1, wherein the information regarding the width W_W is a difference between the widths W_W of successive cycles.