JPH07116852A - Torch for narrow gap mig welding and welding method thereof - Google Patents

Abstract

PURPOSE:To provide a torch for narrow gap MIG welding and welding method thereof capable of obtaining stable good quality weld zone without generating welding defects of blowhole, incomplete penetration, etc., in weld zone. CONSTITUTION:A hole of shield gas injection ports 5, 6 for welding is made to oval shape, improving spreading of shield gas, further a hole of a contact tip of torch is made to oval, by always setting a weaving direction of a welding wire 10 in the fixed direction, high quality weld zone is obtained with suppressing welding defects of incomplete penetration, etc. Shielding effect of welding is improved, reducing welding defects of blowhole, etc., also, the welding wire 10 is weaved in the fixed direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a narrow groove inert gas metal arc (MIG) welding device, and more particularly to a narrow groove MI.
The present invention relates to a narrow groove MIG welding torch suitable for obtaining a high quality guarantee in a G weld and a MIG welding method using the torch.

[0002]

2. Description of the Related Art Conventional inert gas metal arc (MI
G) Welding or welding electrode (consumable) inert gas inlet
The narrow groove MIG welding apparatus using the welding method called “Q welding” corrugates the welding wire 22 by the weaving roller 23 in the process of feeding the welding wire 22 having a small diameter as shown in FIG. After being deformed and passing through the welding torch 21, the welding wire 22 reaching the welding portion 25 is automatically swung by the restoring force of the bending tendency of the welding wire 28 to obtain sufficient penetration into the side wall surface of the groove 28. To do. As a known example related to this type of narrow groove welding device, there is, for example, JP-A-56-36386. As shown in FIGS. 5 to 7, a conventional MIG welding torch used for narrow groove MIG welding has a contact tube 13 serving as a passage of a welding wire 10 as an axis, and a cooling water feed pipe 3 and a cooling water return pipe 4. A front gas passage 1 and a rear gas passage 2 which are shield gas passages are provided, and these are arranged in a line to form a flat plate-shaped welding torch. The torch for MIG welding shown in FIGS. 5 to 7 has been conventionally used for narrow groove welding, but it includes a front gas passage 1 and a rear gas passage 2, a front gas ejection port 16 and a rear gas ejection portion. The outlet 17 has the same sectional shape. In the shape of this gas ejection port, the rear gas ejection port 17, which is the ejection port of the shield gas, is attached to the weld metal 9 in the welding advancing direction 11 shown in FIG. Since they are too close to each other, a secondary arc (series arc) is generated through the shield gas during this period.
Occurs, the welding arc becomes unstable, spatter is easily generated, and the torch is burnt out.
Since the cross section of the welding wire 10 and the hole of the contact tip 14 are both circular when 0 passes through the contact tip 14, the wavy runout of the welding wire coming out of the contact tip 14 is as shown in FIG. , It is not parallel to the side surface of the groove 28 but is tilted like the weaving 20. For this reason, welding defects such as poor penetration easily occur in the welded portion, which has been a problem in narrow gap MIG welding.

[0003]

As described above, in the conventional narrow groove MIG welding, since the welding wire weaves not obliquely to the side surface of the groove but obliquely, welding such as poor penetration into the welded portion occurs. There is a problem that defects are likely to occur.

The object of the present invention is to solve the above-mentioned problems in the prior art, and in narrow gap MIG welding, stable welding of good quality is achieved without causing welding defects such as blowholes and poor penetration in the welded portion. To provide a narrow groove MIG welding torch in which a portion is obtained and a welding method using the torch.

[0005]

The above object of the present invention is to provide M
The gap between the shield gas jet at the tip of the IG welding torch and the deposited metal to be formed is widened to suppress the generation of secondary arc, and at the same time, the hole of the shield gas jet is slanted from the tip of the contact tip. By opening in an elliptical shape (elliptical shape) inclined upward, the diffusivity of the shield gas is improved, and the hole of the contact tip that supplies the welding wire provided at the tip of the MIG welding torch to the welding portion is oval. As a result, the weaving direction of the welding wire is set to the major axis direction of the oval. The present invention is directed to a contact tip provided at the tip of a contact tube for feeding a welding wire, a flat gas passage having a front gas passage and a rear gas passage for sandwiching the contact tube and supplying shield gas in the welding direction. In a narrow groove inert gas metal arc welding torch of various shapes, the lower block of the welding torch is formed into an inverted triangular shape, and the shapes of the holes of the front gas ejection port and the rear gas ejection port of the shield gas are contacted. It is a narrow groove MIG welding torch formed in an elliptical shape that is inclined obliquely upward from the tip end portion.
The present invention also provides a contact tip provided at the tip of a contact tube for feeding a welding wire, a flat gas passage having a front gas passage and a rear gas passage for sandwiching the contact tube and supplying shield gas in the welding direction. In a narrow groove inert gas metal arc welding torch of various shapes, the shape of the contact tip hole for feeding the welding wire at the tip of the welding torch is an ellipse, and the weaving direction of the welding wire is the above ellipse. It is a narrow groove MIG welding torch set in the long axis direction of the hole. Furthermore, the present invention provides a contact tip provided at the tip of a contact tube for feeding a welding wire, a flat gas passage having a front gas passage and a rear gas passage for sandwiching the contact tube and supplying shield gas in the welding direction. For narrow torch inert gas metal arc welding torches with various shapes,
The lower block of the welding torch has an inverted triangular shape,
The holes of the front gas ejection port and the rear gas ejection port of the shield gas are formed in an oval shape inclined obliquely upward from the tip of the contact tip, and the welding wire at the tip of the torch for welding is sent to the welding portion. This is a narrow groove MIG welding torch in which the shape of the contact tip hole to be supplied is elliptical and the weaving direction of the welding wire is set in the major axis direction of the elliptical hole. Further, the present invention relates to a narrow groove MIG welding method, and in the method of MIG welding a narrow groove such as an I-shape by using the above-described narrow groove MIG welding torch of the present invention, from the tip of the contact tip. A gas outlet having an oblong hole is formed by inclining diagonally upward to widen the distance between the deposited metal and the shield gas outlet, and the shield gas ejected from the elliptic gas outlet is provided in the groove. In order to ensure that the welding arc is stable and the welding arc is set to a constant direction, the long axis direction of the oval contact tip hole and the weaving direction of the welding wire are always set to a constant direction. It is a narrow gap MIG welding method for preventing adhesion, suppressing burnout torch burnout, and suppressing welding defects such as blowholes and poor penetration.

[0006]

According to the present invention, the secondary arc is generated by widening the distance between the shield gas ejection port of the narrow groove MIG welding torch and the deposited metal and by making the hole of the gas ejection port oval. Welding at the time of weaving because the nozzle shape of the contact tip through which the welding wire passes, which can suppress it, improves the shielding gas diffusion, and has an oval hole with its major axis aligned with the weaving direction of the welding wire. The bending tendency of the wire can be absorbed, the covering property of the shield gas is improved in the narrow groove welding, and the feeding operation of the welding wire is stabilized. As a result, the narrow groove MI
It is possible to reduce welding defects due to the occurrence of blowholes and poor penetration in G welding, and it is possible to stably obtain high-quality welded portions.

[0007]

Embodiments of the present invention will be described below in more detail with reference to the drawings. Generally, the main piping that constitutes a part of a power generation boiler is a main steam pipe, high-temperature reheat steam pipe, low-temperature reheat steam pipe, main water supply pipe, etc. It has a tube structure. The main piping has a high-temperature, high-pressure piping structure in which high-temperature, high-pressure steam heated by a coil is sent from a boiler to a turbine, and steam that has finished its work in the turbine is returned to the boiler coil again. Further, since the piping itself has high temperature and high pressure, the expansion and contraction amount at the time of starting and stopping the boiler is large, and stress concentrates on the welded joint, so that a high quality welded portion is required for the main piping from the boiler to the turbine. The structure of a typical narrow gap MIG welding torch used for welding these high temperature and high pressure pipes is shown in FIGS. 1 and 2 (a) and 2 (b). Figure 1
2A is a schematic view showing a cross-sectional structure of the tip block portion of the narrow groove MIG welding torch, FIG. 2A is a cross-sectional view of the contact tip of the MIG welding torch, and FIG.
It is a A arrow line view of (a). In the figure, the front gas passage 1
The shield gas supplied from the rear gas passage 2 and the rear gas passage 2 is ejected from the front gas ejection port 5 and the rear gas ejection port 6, and the shape of the holes of these ejection ports 5 and 6 is an oblong ellipse (ellipse). Therefore, the distance between the rear gas ejection port 6 and the deposited metal 9 is widened to prevent the secondary arc from being generated, and the shield gas ejected from the front gas ejection port 5 and the rear gas ejection port 6 has a narrow groove. Since it is sufficiently diffused in the welded portion, welding defects such as blowholes can be suppressed. Furthermore, since the shape of the contact tip hole 12 of the contact tip 8 is an elliptical shape, the welding wire 10 coming out from the contact tip hole 12 always bends regardless of which direction the welding wire 10 is bent. It becomes a fixed direction. FIG. 3A shows the narrow groove MIG of the present invention.
FIG. 3 (b) is a plan view showing an example of the configuration of the welding torch.
FIG. 4 is a view on arrow B of FIG. As shown in the figure, by forming the lower block 15 of the torch in a substantially inverted triangular shape, the distance between the deposited metal and the shield gas ejection port becomes wider, and the secondary arc is prevented and the welding shield gas is diffused better. can do. 4A is a sectional view showing the structure of the lower block of the torch, and FIG.
It is a C arrow line view of (a). The welding shield gas is sufficiently diffused by the front gas ejection port 5 and the rear gas ejection port 6. Then, the elliptical contact tip hole 12 provided in the contact tip 8 makes the deflection direction due to the bending of the welding wire always a constant direction and stabilizes the welding arc. Therefore, it is possible to reduce welding defects due to the occurrence of blowholes, defective penetration, and the like. In MIG welding in an I-shaped narrow groove, as a welding shield gas, argon gas, carbon dioxide gas 15
When welding was performed using a mixed gas of argon and carbon dioxide mixed with 25% by volume, the welding wire could be stably fed, and the gap between the rear gas ejection port of the MIG welding torch and the deposited metal could be improved. No secondary arc (series arc) is generated, there is no turbulence of the arc due to fluctuations in the flow rate of the shield gas, and there is no spatter adhered to the contact tip or burnout of the nozzle. It was possible to reduce welding defects such as poor penetration in the groove wall surface due to the bending of the welding wire, and it was possible to obtain high quality welds. The present invention can be applied not only to the MIG welding torch but also to the TIG welding torch, and it has been confirmed that the same effect as in the case of MIG welding can be obtained.

[0008]

As described in detail above, the M of the present invention
According to the IG welding torch, since the gap between the welding shield gas ejection port and the deposited metal is wide and the ejection port shape is oval, the flow of the shielding gas can be widely diffused. Further, the gas shield effect of the welded portion is improved, and welding defects due to generation of blowholes and the like in the welded portion can be reduced. Further, even if the welding wire supplied from the contact tip is bent, the contact tip hole has an oval shape and can be weaved in a predetermined direction, so that welding defects such as poor penetration can be reduced. A high quality weld can be obtained.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a welding situation by a torch for MIG welding illustrated in an embodiment of the present invention.

FIG. 2 is a schematic view showing a structure of a contact tip of the MIG welding torch exemplified in the embodiment of the present invention.

FIG. 3 is a schematic diagram showing the overall configuration of the MIG welding torch illustrated in the embodiment of the present invention.

FIG. 4 is a schematic view showing a structure of a lower block of the MIG welding torch exemplified in the embodiment of the present invention.

FIG. 5 is a schematic diagram showing the overall configuration of a conventional MIG welding torch.

FIG. 6 is a schematic view showing a structure of a lower block of a conventional MIG welding torch.

FIG. 7 is an explanatory view showing a welding situation by a conventional MIG welding torch.

FIG. 8 is an explanatory view showing a state of weaving in a conventional narrow groove MIG welding torch.

FIG. 9 is an explanatory view showing the overall configuration of a conventional narrow groove MIG welding apparatus.

[Explanation of symbols]

 1 ... Front gas passage 2 ... Rear gas passage 3 ... Cooling water feed pipe 4 ... Cooling water return pipe 5 ... Front gas ejection port 6 ... Rear gas ejection port 7 ... Welding arc 8 ... Contact tip 9 ... Weld metal 10 ... Welding wire 11 ... Welding progress direction 12 ... Contact tip hole 13 ... Contact tube 14 ... Contact tip 15 ... Lower block 16 ... Front gas jet 17 ... Rear gas jet 18 ... Base material 19 ... Nozzle 20 ... Weaving 21 ... Welding torch 22 ... Welding wire 23 ... Weaving roller 24 ... Pull roller 25 ... Welding portion 26 ... Gas nozzle 27 ... Base material 28 ... Groove

Claims (4)

[Claims] 1. A contact tip provided at the tip of a contact tube for feeding a welding wire, and a front gas passage and a rear gas passage for sandwiching the contact tube and supplying shield gas in the welding direction. In a flat shape narrow groove inert gas metal arc welding torch, the lower block of the welding torch is formed into an inverted triangle shape, and the shape of the holes of the front gas ejection port and the rear gas ejection port of the shield gas, A narrow groove MIG welding torch characterized by being formed in an oval shape that is inclined obliquely upward from the tip of the contact tip. 2. A contact tip provided at the tip of a contact tube for feeding a welding wire, and a front gas passage and a rear gas passage for sandwiching the contact tube and supplying shield gas in the welding direction. In the flat shape narrow groove inert gas metal arc welding torch, the shape of the contact tip hole for feeding the welding wire at the tip of the welding torch to the welding portion is an ellipse,
A narrow groove MIG welding torch characterized in that the weaving direction of the welding wire is set in the major axis direction of the oval hole. 3. A contact tip provided at the tip of a contact tube for feeding a welding wire, and a front gas passage and a rear gas passage for sandwiching the contact tube and supplying shield gas in the welding direction. In a flat shape narrow groove inert gas metal arc welding torch, the lower block of the welding torch is formed into an inverted triangle shape, and the shape of the holes of the front gas ejection port and the rear gas ejection port of the shield gas, The contact tip is formed in an elliptical shape inclined obliquely upward from the tip, and the shape of the contact tip hole for feeding the welding wire at the tip of the welding torch to the weld is oval, and the weaving direction of the welding wire. Is set in the major axis direction of the oval hole, and the torch for narrow groove MIG welding is characterized in that. 4. A method of MIG welding a narrow groove using the MIG welding torch according to any one of claims 1 to 3, wherein a shield gas ejection port is obliquely upward from a tip of a contact tip. Forming a slanted ellipse to widen the distance between the weld metal and the shield gas ejection port, eject the shield gas from the elliptical gas ejection port into the narrow groove, and sufficiently diffuse it. By setting the long axis direction of the contact tip hole and the weaving direction of the welding wire to be always constant, it is possible to prevent spatter adhesion, suppress blowholes, and suppress welding defects due to poor penetration. Characteristic narrow groove MIG
Welding method.