JPS60162578A - Method for controlling groove profiling in gas shielded metal arc welding - Google Patents

Abstract

PURPOSE:To control easily and economically a torch so as to profile exactly a groove line by ejecting alternately a control gas having the potential inclination different from the potential inclination of a shielding gas from both right and left sides of a welding torch and controlling the movement of the welding torch in the transverse direction of the groove so that the right and left arc lengths are made equal. CONSTITUTION:A shielding gas (Ar, etc.) is ejected around the arc 5 generated between the top end of a welding wire 3 and materials 4 to be welded from a nozzle 6 to shut off air. A control gas (gaseous carbon dioxide) 8 is alternately ejected for specified time from holes 1a, 1b punched on both sides at the bottom end of a welding torch 1 in this state to oscillate the arc 5 to the right and left around the wire 3. The arc voltage when the arc 5 is oscillated to the right side wall 4b and left side wall 4a of the groove is detected and the torch 1 is moved in the transverse direction of the groove so that the arc lengths lR, lL are made equal. The torch 1 is thus moved to profile the weld line.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a groove tracing control method in gas seven-metal arc welding.

[Prior art]

An arc is generated between the bath welding wire and the base metal, and this arc is used as a heat source to melt the welding wire and the base metal, and a shielding gas such as argon or carbon dioxide is flowed around it to isolate the welded part from the surrounding air. During gas-shielded metal arc welding, the torch position is automatically detected and the torch is controlled so that the torch accurately follows the groove line.

Detection of the torch position is generally carried out using various types of sensors, including contact sensors such as limit switches, and non-contact sensors such as electromagnetic or optical sensors, and the torch is moved and adjusted in the groove width direction based on this information.

However, contact type sensors require the sensor to be placed near the welding position using a complex mechanism, while non-contact type sensors are located near the arc, which is greatly affected by heat and light, causing various practical problems. .

[Purpose of the invention]

The present invention has been made in view of the above points, and an object of the present invention is to provide a simple and economical method for causing a torch to accurately follow a groove line without requiring a complicated mechanism.

[Structure of the invention]

In order to achieve the above object, the present invention generates an arc between a welding wire and a workpiece, and gas-shielded metal arc welding is performed by ejecting a shielding gas such as argon or carbon dioxide around a t-weld part. In this method, a control gas having a potential gradient different from that of the shielding gas is injected in the vicinity of the arc alternately from the left and right sides in the direction of movement of the welding torch, so that the welding material can be welded in the width direction of the groove. It is characterized by oscillating the arc, detecting changes in the left and right arc lengths using electrical signals, and controlling the movement of the bath welding torch in the width direction of the groove so that the left and right arc lengths are equal.

〔Example〕

Embodiments of the present invention will be described based on FIGS. 1 to 3.

FIG. 1 is a diagram for explaining the present invention in detail. In normal gas-shielded metal arc welding, the voltage applied by the welding power source is passed through the welding wire 3 through the tact tip 2 provided at the tip of the welding torch 1. An arc 5 is applied between the tip of the welding wire 3 and the workpiece 4, and an arc 5 is applied between the tip of the welding wire 3 and the workpiece 4.
The area around the arc 5 where the welding torch 1 is generated is covered with a shielding gas 7 such as argon discharged from a gas nozzle 6 installed near the welding torch 1 to block air.

In this state (the shielding gas 7 is argon gas), when carbon dioxide gas is ejected as the control gas 8 from the hole 1a drilled at the lower end of the welding torch 1 shown in Fig. 1, the arc 5 is ), the welding wire 3 is swung to the opposite side of the hole 1a.

This is because the ejected carbon dioxide gas is attracted by the high-speed plasma airflow of the arc column and forms a layer of carbon dioxide gas, and since carbon dioxide gas has a higher ionization voltage than argon gas, arc 5 is on the argon gas side with a lower potential gradient. This is because it appears to be swung to the opposite side of the hole 1a.

Similarly, when the control gas 8 (carbon dioxide gas) is ejected from the hole 1b drilled at the lower end of the welding torch 1, the arc 5 is directed to the opposite side of the hole 1b with the welding wire 3 as the center, as shown in FIG. 1(C). It will be in a shaken state.

By repeating this operation alternately, that is, 8 t of control gas
The shear arc 5 is oscillated left and right around the welding wire 3 by ejecting it alternately from the holes 1a and 1b for a certain period of time.

Now, when the welding wire 6 is at the center of the groove, the arc length tR when the arc 5 is generated toward the right side wall 4b of the groove
The arc lengths tL are the same when the arc occurs on the left side wall 4a of the groove, but if the welding wire 3 deviates from the center of the groove, the arc lengths tR and tL are not equal.◎ For example, when the welding wire 3 If the center is shifted to the left, arc length tR>arc length tL, and if it is shifted to the right, arc length tR<arc length tL.

This arc length is determined by the arc voltage (E) or the welding current (i)
is in a proportional relationship, and if arc length tR>arc length LL, the voltage ER when an arc is generated on the right side wall 4b (
Alternatively, the welding current IR) is p larger than the voltage EL (marginal welding current 1x) when an arc occurs on the left side wall 4a, and the opposite is true when arc length t's>arc length LL.

Therefore, while the welding torch 1 is moving in the groove direction, the control gas 8
The change in arc voltage E or welding current IO when the arc 5 swings between the right side wall 4b and the left side wall 4aK of the groove is detected by ejecting it alternately from the holes 1a and 1b, and the bath welding torch is adjusted so that these are equal. 1 in the width direction of the groove, the welding torch 1 follows the center of the groove, that is, the welding line.

Note that it is also possible to use carbon dioxide gas as the shield gas and argon gas as the control gas, contrary to the above description. In this case, the arc 5 is generated by being swung to the opposite side to that shown in FIG. 1, that is, to the side from which the control gas is ejected. Generally, shielding gases include argon, carbon dioxide, helium, or a mixture of these gases; however, by selecting a control gas that has a potential gradient different from that of the shielding gas, this method can be used without particular limitation. Inventions can be put into practice.

Next, an embodiment of the method of the present invention will be described with reference to FIGS. 2 and 6. FIG. 2 shows a welding state using the groove tracing control device according to the embodiment of the present invention.

That is, a support 12 is provided on a truck 11 that runs on a rail 10 laid approximately parallel to the groove line direction of the workpiece 4, and a drive arm 13 is provided on this support. The welding torch 1 is movably attached to the drive arm 16 with a pole screw or the like. A torch drive motor 14 for moving the welding torch 1 is mounted on the upper part of the column 12.

In addition, a wire reel 15, a wire feed motor 16, and a control box 17 for controlling welding conditions and the movement of the bath welding torch 1i are mounted on the trolley 11, and a DC welding machine 18 and a shield gas cylinder are mounted on the ground. 19 and a control gas cylinder 20 are provided; 21 is a manual handle for moving the welding torch 1 in the vertical direction; 22 and 23 are hoses for shielding gas and control gas; 24 is a cable.

Next, an example of the control system for groove tracing in the above embodiment will be explained with reference to FIG.

Control gas 8 is alternately switched at regular intervals via a solenoid valve (not shown) in control box 17 to
It is supplied to a and jb. That is, when the solenoid SR on the right side of the electromagnetic valve is energized, control gas is ejected from the hole 1a, and when the solenoid SL on the left side is energized, the control gas is ejected from the hole 1b. Then, the arc voltages EL and ER are detected at each time, and rEn-Hr and r are calculated and compared with the specified value α.

This specified value α is an allowable value of the bath tangent in the groove width direction. I
If gu -ELl is smaller than the specified value α, the torch drive motor 11tf is in a stopped state, but if IEu-Fibl is larger than the specified value α, the magnitude of the arc voltage HR and the arc voltage EL are compared, and the torch drive motor 14 is stopped. The welding torch 1 is controlled to be rotated to the left or right and moved in the width direction of the groove so that the welding torch 1 is always located at the center of the bath tangent.

In the above explanation, the workpiece to be welded has a V-groove, but it is not limited to this, and can be used for joints where the left and right arc length changes when the arc is oscillated and deviates from the welding line. Of course.

As explained above, this process uses a control gas to oscillate the arc in the groove width direction around the welding wire, and if there is a difference between the left and right arc lengths, the bath welding torch is automatically adjusted so that the arc lengths are equal. I decided to move it, so
Even if the weld line direction is off or the groove width fluctuates, the weld line will be reliably traced, and there is no need to install a sensor near the weld to detect deviations from the bath tangent as in the past. This is a simple, compact, and durable method.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the principle of the method of the present invention, Fig. 2 is a front view showing the welding state by the m-contact m-patching control device of the embodiment of the present invention, and Fig. 3 is a control system diagram of the embodiment. It is. 1 is a bath welding torch, Ia, 1b is a control gas injection hole, 2 is a contact tip, 3 is a welding wire, 4 is a workpiece to be welded, 5 is an arc, 6 is a gas nozzle, 7 is a shielding gas, 8 is a control gas, 10 11 is a trolley, 12 is a column, 13 is a drive arm, 14 is a torch drive motor, 15 is a wire reel, 16 is a wire feeding motor, 17 is a control box, 18 is a DC welding machine, 19 is a shield gas pump , 20 is a control gas cylinder, 21 is a manual handle, 22.23 gas hose, and 24 is a cable. Patent Applicant Nippon Sharyo Misakizo Co., Ltd. Procedural Amendment May 1, 1985 Commissioner of the Patent Office Mr. Manabu Shiga fl, Incident Indication 1982 Patent Application No. 17416 2, Name of Invention Gas Shield Metal Arc Welding Relationship between the groove tracing control method 3 and the case of the person making the amendment Patent applicant (461) Nippon Sharyo Manufacturing Co., Ltd. 4 Voluntary submission by the agent 6 Number of inventions increased by amendment 7 Subject of amendment (1 ) “or welding current (I)
) J, delete [(or welding current IL) J from lines 13 to 14 of the same page. (2) Delete "or welding current ■" on page 8, line 4 of the same book. that's all

Claims (1)

[Claims] 1. Generate an arc between the welding wire and the workpiece,
In gas-shielded metal arc welding, which is performed by ejecting a shielding gas such as argon or carbon dioxide around the welding part, a control gas with a different potential gradient from the above-mentioned shielding gas is applied to the left side of the direction of travel of the welding torch. By ejecting alternately from the right side near the arc, the arc is oscillated in the width direction of the groove of the W welded workpiece, and fluctuations in the left and right arc lengths are detected by electrical signals, so that the left and right arc lengths are equalized. A groove tracing control method in gas-shielded metal arc welding, characterized by controlling the movement of a welding torch in the width direction of the groove.