JPH10193106A - Method for automatically welding circumference of tube and controller therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the welding speed and the bead appearance by using a pre-set welding mode judging logic table and automatically changing a pulse arc welding and a shot arc welding corresponding to the welding condition in the advancing stage of welding in the time of welding the total circumference of tube ends fixed with butting. SOLUTION: In comparison with the welding mode judging logic table which is pre-set corresponding to the arc characteristic condition, the condition between layers, the welding attitude, and these respective conditions, and the laminating logic table based on the information inputted in an automatic welding controller of the laminated numbers 1 to 6, the laminate height h1 to h6 , the laminate width w1 to w2 , the welding position in the circumferential direction, the welding attitude, etc., the welding mode in each welding site is judged automatically and the suitable welding parameter is set. Further, based on this welding parameter, the operation program is made, following this, welding is started, corresponding to the welding object, the welding mode is changed automatically as it is pre-set.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for automatically welding a pipe circumference, and more particularly to a method and an apparatus capable of automatically switching between a pulse arc welding mode and a short arc welding mode to perform welding. .

[0002]

2. Description of the Related Art At the time of laying a gas pipeline, the end faces of two pipes fixed in abutting manner are connected by full circumference welding. When this welding is performed by automatic welding, a belt-like guide rail is wound around a pipe, and a welding head is run on the guide rail to perform welding by a MAG (metal active gas) method or the like.

Conventionally, arc welding is roughly classified into pulse arc welding and short arc welding.

In pulse mag welding, a pulsed current as shown in FIG. 8A is used. In the droplet transfer, a pinch force acts on the droplet at the tip of the wire by a sharp pulse current higher than the critical current, and the transfer of one droplet per pulse is preferably performed in synchronization with the pulse.

In short arc welding, the welding current has a non-pulse current waveform as shown in FIG.
Welding is performed by "short circuit transfer" in which the droplet at the tip of the wire melted by the arc comes into contact with the surface of the molten pool and transfers to the base material. In this case, since a power supply having a constant voltage characteristic is usually adopted as the welding power supply, a high short-circuit current flows when the droplet is short-circuited, the short-circuit portion is narrowed down by the electromagnetic pinch force, the short-circuit is broken, and the arc is broken. Plays.

[0006]

When comparing the two types of arc welding, pulse arc welding is capable of welding a large amount of welding with a high current, but is unstable in a low current range. Therefore, the pulse arc welding mode is not suitable for a case where it is desired to perform welding slowly in consideration of the beauty of the bead formation and the like. Conversely, short arc welding is not good at welding in a high current range, and its welding amount is low, so it is not suitable for high-speed welding with a high welding amount.

Accordingly, the present invention provides a method and apparatus for automatically welding a pipe circumference taking into account both welding speed and bead appearance by combining pulse arc welding and short arc welding according to the welding object and scene. The purpose is to provide.

[0008]

SUMMARY OF THE INVENTION The present invention relates to a method for automatically welding a pipe circumference, which welds the end faces of two pipes fixed in abutting manner, under a predetermined condition.
The welding is performed by automatically switching between the pulse arc welding mode and the short arc welding mode.

The predetermined condition includes, for example, at least one of a layer to be welded at the time of laminating and welding a plurality of times, and a current welding posture.

[0010] By this method, it is possible to perform automatic pipe circumferential welding taking into account both the welding speed and the aesthetic appearance of the bead, taking advantage of both pulse arc welding and short arc welding.

The present invention also relates to a pipe circumference automatic welding control device for welding the end faces of two pipes which are fixed in abutting manner, in a pulse arc welding mode and a short arc welding mode under various conditions. A welding mode determination table for determining which welding mode to select, and each layer of the number of laminations determined based on input information including at least the diameter, plate thickness, groove angle of the pipe to be welded and Means for determining welding modes for various conditions by comparing various conditions including the welding position with the welding mode determination table, means for determining various welding parameters in the determined welding modes, and the determined welding Control means for controlling the welding power source and the welding head based on the parameters.

By providing a welding mode determination table, only input information and various conditions are given, and a welding mode suitable for them is automatically selected.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings.

Referring to FIG. 1, a schematic configuration of a welding apparatus according to the present invention will be described. The personal computer 1 is for creating CAD data (design values such as the outer diameter, thickness, material, and groove shape of a pipe) for automatic welding control, and the created data is a flexible disk (floppy disk). Disc 1a. The control device 2 performs a substantial control of the automatic welding (control of a power supply and a torch position, etc.).
And reads the CAD data from the flexible disk 1a in which the CAD data is stored. Of course, data transfer may be performed by well-known data communication without using a flexible disk. The control device 2 sets actual welding conditions using the read data, and sets various welding parameters in accordance with the set conditions by using data previously recorded in a logic table described later.

Further, the control device 2 converts the set welding parameters into NC language (language for numerical control) used for actual welding control, and uses the converted language as control data in the form of a control data table. Record in memory. The power supply 3 and the welding head 4 are driven and controlled using the control data recorded in the memory. The main control items of the control device 2 are the welding voltage and current of the welding head 4, the weaving of the welding torch 8 mounted on the head 4 with respect to the pipe groove, the moving speed of the welding head 4, and the like. The head 4 is mounted on a guide rail 12 wound on the outer periphery of the pipe so as to be movable in the circumferential direction. The head 4 is provided with a wire supply unit 6 for supplying a welding wire to the welding torch 8.

FIG. 2 shows the internal configuration of the control device 2 and the power supply 3 and the electrical connection between them and the torch 8 of the head 4 and the pipe 5. From the power source 3, a wire 7 of the head 4 is connected via a power transmission cable (not shown).
A welding voltage is applied between the pipe and the pipe 5. Thereby, an arc is generated between the wire 7 and the surface of the pipe 5. The welding wire 7 is sent at a constant speed,
It is melted by the arc to become a deposited metal, which solidifies within the groove and joins the base material 5.

The control device 2 has a storage device 201 such as a hard disk which stores a welding database in which predetermined welding conditions and welding parameters are stored in a table format as a logic table (described later). In response to this, various input information such as current I, voltage V, wire diameter, wire brand, etc. are given, and a welding NC operation command corresponding to these is obtained in the form of an operation program 203. The operation program 203 is executed by the CPU 205. The CPU 205 realizes a function of outputting various commands to the welding power source 3, a function of receiving a core velocity signal, a measurement of a current / voltage waveform, and the like. Although not shown, the memory used during the operation of the CPU is included in or outside the CPU 205. The various commands for the welding power source include a command current value I10, a base current value Ib, channel selection information, a current pulse width tp, and a command voltage value V10, respectively, including DA converters 211 and 212, a channel selector 213, and a DA converter 214. , 215 to the power supply 3. In addition,
When operating in the short arc welding mode, commands for the base current and the pulse width are unnecessary. Power supply 3
Mode switching command M to switch the welding mode
ODE is supplied to the power supply 3. The output Itg of the tacho generator TG, which will be described later, is sent to the CPU via the AD converter 216.
205. The control device 2 includes a pulse measurement circuit 217 that receives a current feedback (FB) waveform Ifb and a voltage feedback waveform Vfb from a power supply and measures various waveform parameters. Such a pulse measuring circuit 217 is for actually measuring various parameters from a welding current waveform and a welding voltage waveform and using the measured parameters for arc copying correction and the like. It is disclosed in, for example, JP-A-8-74036.

The welding power source 3 supplies a current command 301 from the control device 2 to the motor M of the wire supply unit 6 via the amplifier 303. The speed feedback signal of the tachogenerator TG for detecting the rotation speed of the motor M is supplied to the AD converter 216 of the control device 2 as described above. The welding power source 3 can operate in either the pulse welding mode or the short arc welding mode in response to the welding mode switching command MODE, and has a control unit 305 including a power control unit 3051 and a control logic unit 3052. The control unit 305 controls the base current Ib306 and the pulse current Ip30 from the control device 2 in the pulse arc welding mode.
9. Upon receiving the pulse width tp and the voltage command 311, a pulse output meeting these conditions is supplied to the head. The pulse current Ip 309 is obtained by selecting one of a plurality of pulse current setting values in the ROM table 308 based on the channel selection information 307 from the control device 2. ROM
The table 308 has a pulse current I as its output in the figure.
Although only p is shown, a set of the pulse current Ip and the pulse width tp is output. The pulse width tp 310 indicates a fine adjustment amount of the pulse width tp output from the ROM table 308. In the short arc welding mode, the power supply 3 receives the voltage command 311 and supplies a voltage output meeting the condition to the head. The welding current feedback value SI10 and the welding voltage feedback value SV10 are averaged by a current meter 314 and a voltage meter 313, respectively, and are supplied to the above-described pulse measurement circuit 217.

Next, the operation of the present embodiment will be described with reference to the flowcharts of FIGS. This processing can be executed by the CPU 205 of the control device 2.

In FIG. 3, the CPU 205 first receives an input of the diameter, plate thickness, groove angle, etc. (FIGS. 5A and 5B) of the pipe to be welded from the operator (S301).
Thereafter, a numerical value representing an arc characteristic condition considered appropriate for this welding is received from the operator (S3).
02). The arc characteristic condition determines when to select the short arc welding mode, and is determined in advance in the present embodiment as follows.

3: Upward posture, finishing layer, Urabami layer (first layer) 2: Finishing layer, Urabami layer 1: Urabami layer *: All pulse arc welding 4: All short arc welding Here, "*" means don't care Is shown. The user inputs such numerical values as arc characteristic conditions. Based on this, automatic switching of the welding mode as described later is set.

Next, a stacking plan is performed by referring to the input information in the stacking plan logic table 201a (S30).
3). In this stacking plan, the number of stacks and the height of each stack (FIG. 5)
(C)), groove width (determined from groove angle and plate thickness),
Automatic setting of the welding posture, address (position in the circumferential direction of the pipe) and the like are performed. As shown in FIG. 5D, the welding position is determined such that the ranges of the downward, vertical, and upward postures are, for example, the downward range is from 0:00 to 2:00. I do. The details of the logic table 201a and the creation of welding data using the logic table 201a are disclosed in Japanese Patent Application No. 7-173921 previously proposed by the present applicant.

Subsequently, the logic table 201 for determining the welding mode is added to the lamination plan determined in this manner.
The welding mode in each scene (layer or posture) is automatically determined with reference to b, and various welding parameters preferable for them are set (S304 to S317).

Specifically, first, a layer, a rotation direction, and a posture are selected (S304, S305, S306), and the welding mode determination logic table 201 is referred to for these.

FIG. 6 shows an example of the welding mode determination logic table 201. Each row 2016 of the table 201b includes an arc characteristic condition 2011 and an interlayer condition 20.
12, an attitude condition 2013, and a welding mode 2014. The arc characteristic conditions are as described above. For example, in the first row of this table, when the input value of the arc characteristic condition is 4 or more, regardless of which layer is the current layer or what the attitude is, , Welding mode "9"
(In this example, short arc welding) is selected. In the second line, if the input value of the arc characteristic condition is 3 or more, the welding mode “9” is set in the upward posture.
That is, it indicates that the short arc welding mode is selected. The third line indicates that if the input value of the arc characteristic condition is 2 or more, the welding mode “9”, that is, the short arc welding mode is selected for the finishing layer. Similarly, the fourth line indicates that if the input value of the arc characteristic condition is 1 or more, the welding mode “9”, that is, the short arc welding mode, is selected for the Uranami layer. The fifth line indicates that the welding mode “1”, that is, the pulse arc welding mode, is selected for the Uranami layer for any numerical value of the arc characteristic condition. The sixth line indicates that the welding mode “6”, that is, the pulse arc welding mode is selected for all the numerical values of the arbitrary arc characteristic conditions. The difference between welding modes "1" and "6" is
As shown in FIG. 7, the pulse value Ip and the pulse width t are respectively shown.
It corresponds to the different combinations of p and is specified by the channel selection information 307 described in the control device 2 of FIG.

Consider, for example, a case where an input value "3" of the arc characteristic condition is given to the table 201b of FIG. In this case, since it is less than “4”, it does not correspond to the first row, and corresponds to “3” or more in the second row. Therefore, the welding mode “9” is selected for the “upward” posture, which is the condition of the row. Next, it corresponds to the third line. In the third line, the welding mode “9” is selected for the “finishing layer”. Furthermore, it corresponds to the fourth line,
The welding mode “9” is selected for “Ura-wave layer”. Further, although this corresponds to the fifth line, this specifies the pulse arc welding mode for the Uranami layer, and this condition is ignored because it collides with the determination result of the upper line (the fourth line). . Similarly, the item corresponding to the sixth line is ignored, but an item that collides with the determination in the upper line is ignored. After all, for the input value “3” of the arc characteristic condition, as described above, the short arc welding mode “9” is selected for “upward”, “finish layer”, and “backside layer”, and For the layer and the posture, the welding mode “6” that is the pulse arc welding is selected. When the input value of the arc characteristic condition is “0”, the welding mode “1” is selected for the Uranami layer, and the welding mode “6” is selected for the other layers and postures.

In the example shown in FIG. 6, a column for the direction of rotation of the head around the pipe is not provided, but may be provided if necessary.

Returning to FIG. 3, the welding mode is determined for the given layer, rotation direction and posture by the method described with reference to FIG. 6 (S307). Accordingly, when the pulse arc welding mode is selected, welding parameters suitable for the selected mode are set (S308). Further, the automatic copying parameters are set (S309). The welding parameters in each welding mode correspond to the welding power source command output in FIG. Details of the automatic copying parameters are disclosed in the aforementioned Japanese Patent Application No. 8-74036. Similarly, when the short arc welding mode is selected, a welding parameter suitable for the short arc welding mode is set (S310), and the automatic copying parameter is set (S31).
1).

Next, if there is the next posture (S312),
The posture is changed (S313), and the process returns to step S307 to determine a new welding mode. When all postures are completed, the welding mode is determined for the next rotation direction (S
314, S315). Further, these procedures are performed by changing layers (S316, 317).

The above-described operation program 203 (or control data table) is created based on these parameters.

Next, proceeding to FIG.
Automatically starts welding according to In the figure, the processing of FIG. 4 is performed continuously from the processing of FIG. 3, but the processing of FIG. 4 may be performed after an instruction from the operator.

In FIG. 4, the layer, the rotation direction, and the posture are sequentially selected (S318, S319, S320), and the welding power source 3 is selected according to the previously set operation program.
And the welding head 4 is controlled (S321). In parallel with this, arc sensing, current / voltage sampling,
Torch position (up / down, left / right) control, pulse accent prevention control,
Various arc scanning controls such as arc voltage control are performed (S32
2). Such control is repeated by sequentially updating the attitude, the rotation direction, and the layer (S323, S324, S325, S
326, S327, S328).

With the above configuration and operation, automatic welding can be performed while automatically switching the welding mode as set in advance according to the welding target.

While the preferred embodiment of the present invention has been described above, the specific contents of the system configuration and processing are merely examples, and various modifications and changes may be made without departing from the scope of the claims.
Changes are possible. In the above description, the short arc welding mode is selected based on the layer and the posture. However, the short arc welding mode may be specified for a specific address in the layer selected in the pulse welding mode. This can also be performed in the stacking plan S303.

[0035]

According to the present invention, by automatically combining pulse arc welding and short arc welding according to the welding target or scene, automatic pipe circumferential welding is performed in consideration of both the welding speed and the beautiful appearance of the bead. It becomes possible. In addition, since the welding device is automatically operated according to a preset procedure, as long as appropriate welding conditions are input,
The operator may be a beginner.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a schematic configuration of an automatic pipe circumference welding apparatus according to the present invention.

FIG. 2 is a block diagram showing an internal configuration of a control device and a welding power source shown in FIG.

FIG. 3 is a flowchart showing an operation of the control device shown in FIG. 2;

FIG. 4 is a flowchart showing a process following the process of FIG. 3;

FIG. 5 is an explanatory diagram of various input information in steps S301 and S303 of FIG. 3 and conditions determined by a stacking plan.

FIG. 6 is a configuration diagram of a welding mode determination logic table referred to in step S307 of FIG. 3;

FIG. 7 is a pulse current waveform diagram for describing a difference between welding modes “1” and “6” shown in FIG. 6;

FIG. 8 is a current waveform diagram for explaining a difference between pulse arc welding and short arc welding.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Computer, 2 ... Control device, 3 ... Power supply device, 4 ...
Head, 5: Pipe, 6: Wire supply unit, 7: Wire,
8: welding torch, 12: guide rail, 201b: logic table for welding mode determination.

Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI B23K 9/127 509 B23K 9/127 509D (72) Inventor Seiji Minakami 6-8-6 Hanakoganei, Kodaira-shi, Tokyo (72) Inventor Mibu Ikuo 2982-3 Sugaya, Naka-machi, Naka-gun, Ibaraki Prefecture (72) Inventor Kenichi Maeda 1225-47 Tenjinbayashi-cho, Hitachiota, Ibaraki Prefecture

Claims (3)

[Claims] 1. A method for automatically welding a circumference of a pipe, which welds the end faces of two pipes fixed in abutting manner, to a pulse arc welding mode and a short arc welding mode under predetermined conditions. Automatic welding of a pipe circumference characterized in that welding is performed by automatically switching the welding method. 2. The method according to claim 1, wherein the predetermined condition includes at least one of a layer to be welded at the time of laminating and welding a plurality of times, and a current welding posture. The method for automatically welding a pipe circumference according to claim 1, wherein: 3. A pipe circumference automatic welding control device for welding the end faces of two pipes fixed in abutting manner, wherein the welding is performed in any of a pulse arc welding mode and a short arc welding mode under various conditions. A welding mode determination table for determining whether to select a mode, and each layer of the number of layers determined based on input information including at least the diameter, plate thickness, and groove angle of a pipe to be welded, and a welding position are included. Means for determining a welding mode for various conditions by comparing various conditions with the welding mode determination table; means for determining various welding parameters in the determined welding mode; and based on the determined welding parameters. A control means for controlling a welding power source and a welding head, and a pipe circumference automatic welding control device comprising: