JP2005177822A - Gas shield welding method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-cost gas shield welding method and an apparatus therefor where maintenance is facilitated, and spatters are reduced. <P>SOLUTION: Using a main nozzle 3a provided at the tip of a welding torch 3, carbon dioxide 20 protecting a molten pool 24 from the air is made to flow. Further, using an additional gas nozzle 8 with a fine diameter provided at the outside of the welding torch 3, a small amount of inert gas 21 is locally sprayed toward the part of an arc 22 formed at the tip part of the welding torch 3, thus the form in the transfer of droplets is controlled to spray transfer where spatters are reduced. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a welding method and apparatus using a gas shield system.

As an arc welding method, a carbon dioxide gas arc welding method using 100% CO ₂ gas as a shielding gas is a welding method excellent in efficiency and cost, and is often used for products such as bridges and transporters.

Japanese Patent Publication No. 7-36958

  The carbon dioxide arc welding method has a drawback that the droplet transfer form becomes globule transfer in a large current region, and spatter frequently occurs. A specific example is shown in FIG. In FIG. 7, the base material 31, the welding wire 32, the welding torch 33, the carbon dioxide gas 34, the arc 35, the droplet 36, and the base metal molten pool 37 are shown. As a welding phenomenon, the arc 35 is contracted due to the high potential gradient of the arc of the carbon dioxide gas 34 and the anode point at the tip of the welding wire 32 tends to be concentrated at one point, and the droplet is generated by an electromagnetic pinch effect. 36 is pushed upward, and the large droplet 36 tends to grow. Then, when the massive droplet 36 that has been pushed up separates from the end of the welding wire 32, spatter frequently occurs. This spatter not only deteriorates weldability, but also accumulates on the shield nozzle, disturbs the flow of shield gas, induces welding defects, requires removal of spatter attached to the product, etc. There are many disadvantages, and there is a high need for spatter-less.

Currently, there are the following methods for reducing spatter in an arc welding method for performing gas shielding.
1) Droplet transfer control by controlling the current waveform (pulse waveform) of the welding power source.
2) Droplet transfer control by feed wire speed control.
3) A multicomponent mixed gas mainly composed of an inert gas such as Ar, which is less sputtered, is used as a shielding gas.
4) A double gas shield nozzle is used, and an inert gas is used for the inner nozzle (see FIG. 7B).

In the methods 1) and 2), spatter is reduced by preventing short circuits and the like, and in order to improve the welding apparatus itself, an expensive high-accuracy control apparatus is necessary, and the apparatus cost increases. . In addition, these methods basically aim to reduce spatter in the short-circuit transition in the small to medium current region, and the spatter reduction effect in the globule transition in the large current region cannot be expected so much.
In the method 3), since the potential gradient of the multi-component gas mixture is different from that in the case of carbon dioxide gas, the properties of the arc and the form of droplet transfer are essentially changed. Reduction effect can be expected. Moreover, an expensive apparatus is also unnecessary. However, the multi-component mixed gas is about 2 to 5 times more expensive than cheap carbon dioxide gas, and the gas cost is high for use at the work site, which becomes a big bottleneck.
In the method 4), the structure of the double gas shield nozzle (outer nozzle 38, inner nozzle 39) becomes complicated, and maintenance such as cleaning and replacement of the nozzle and the welding tip becomes difficult. When spatter occurs, the gap between the welding tip and the inner nozzle 39 is narrow, so that the welding tip and the inner nozzle 39 are integrated and may not be removed. Therefore, it is difficult to make the inner nozzle 39 more compact than necessary, and it is also difficult to reduce the amount of the expensive inert gas 40 used for the inner nozzle 39. In addition, when spatter adheres to the outer nozzle 38 and the inner nozzle 39, the gas shield becomes defective and there is a possibility of causing a welding defect (see FIG. 7B).

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a gas shield welding method and apparatus that are low in cost, easy to maintain, and reduce spatter.

The gas shield welding method according to the present invention for solving the above problems is as follows.
Using the main nozzle provided at the tip of the welding torch, while flowing the first gas that protects the molten pool from the atmosphere,
Using one or more external nozzles provided outside the welding torch, a second gas having a composition different from that of the first gas is directed toward an arc portion formed at the tip of the welding torch. It is characterized by spraying.
For example, a carbon dioxide gas is used as the first gas, and an inert gas such as Ar or a binary or ternary mixed gas containing an inert gas as a main component is used as the second gas. Further, the second gas may be such that the same component gas is injected from a plurality of external nozzles, or a different component gas may be injected from each of the plurality of external nozzles.

The gas shield welding method according to the present invention for solving the above problems is as follows.
In the gas shield welding method,
The second gas is injected from the external nozzle so that the arc portion is included in at least a potential core region formed by the second gas.
That is, by locally shielding the arc portion with the potential core region formed by the second gas, the droplet transfer mode is controlled to spray transfer with less spatter. Here, the potential core region refers to a region where the second gas penetrates the first gas with little deflection and concentration diffusion by the first gas.

The gas shield welding method according to the present invention for solving the above problems is as follows.
In the gas shield welding method,
As the external nozzle, an inner diameter of 1/10 or more of the inner diameter of the main nozzle is used.

The gas shield welding method according to the present invention for solving the above problems is as follows.
In the gas shield welding method,
The flow rate of the second gas injected from the external nozzle is in a range of 2 to 12 times the flow rate of the first gas flowing from the main nozzle.

The gas shield welding method according to the present invention for solving the above problems is as follows.
In the gas shield welding method,
The flow rate of the second gas injected from the external nozzle is set to 5 L / min or less.

The gas shield welding method according to the present invention for solving the above problems is as follows.
In the gas shield welding method,
Using the arc position detection means for detecting the position of the arc part, detecting the position of the arc part,
A nozzle position control means for controlling the arrangement position of the external nozzle is used to control the injection direction of the second gas based on the position information detected by the arc position detection means.
As the arc position detection means, there is a CCD camera or the like based on an image. In addition, a luminance sensor based on light, a temperature sensor based on heat, or the like may be used.

The gas shield welding apparatus according to the present invention that solves the above problems is as follows.
A welding torch having a main nozzle for flowing a first gas protecting the molten pool from the atmosphere;
One or a plurality of external nozzles that are provided outside the welding torch and inject a second gas having a composition different from that of the first gas toward an arc portion formed at a tip of the welding torch;
It is characterized by having.

The gas shield welding apparatus according to the present invention that solves the above problems is as follows.
In the gas shield welding apparatus,
The injection condition of the second gas at the external nozzle is set so that the arc portion is included in at least a potential core region formed by the second gas.

The gas shield welding apparatus according to the present invention that solves the above problems is as follows.
In the gas shield welding apparatus,
As an injection condition, the inner diameter of the external nozzle is 1/10 or more of the inner diameter of the main nozzle.

The gas shield welding apparatus according to the present invention that solves the above problems is as follows.
In the gas shield welding apparatus,
As an injection condition, the flow rate of the second gas injected from the external nozzle is in the range of 2 to 12 times the flow rate of the first gas supplied from the main nozzle.

The gas shield welding apparatus according to the present invention that solves the above problems is as follows.
In the gas shield welding apparatus,
As an injection condition, the flow rate of the second gas injected from the external nozzle is 5 L / min or less.

The gas shield welding apparatus according to the present invention that solves the above problems is as follows.
In the gas shield welding apparatus,
Arc position detection means for detecting the position of the arc portion;
Nozzle position control means for controlling the arrangement position of the external nozzle based on the position information of the arc portion detected by the arc position detection means to control the injection direction of the second gas;
It is characterized by having.

  According to the present invention, since the inert gas is injected to the arc portion using the external nozzle provided outside the welding torch, maintenance is easy and the equipment cost is low, and the arc portion is shielded with the inert gas. Thus, the occurrence of spatter can be significantly reduced. In addition, as a result of the reduction of spatter, the post-treatment man-hours after welding can be greatly shortened.

  In addition, according to the present invention, since the inert gas injection conditions are set based on the jet theory, it is possible to reliably control the droplet transfer mode to spray transfer and to reliably reduce the occurrence of spatter. .

  In the present invention, carbon dioxide gas is used as the main shield gas for protecting the entire molten pool from the atmosphere, and the outside of the welding torch, that is, a small diameter provided on a separate axis from the main shield gas nozzle. By using a gas nozzle to inject a small amount of inert gas or a mixed gas mainly composed of inert gas toward the arc part, the droplet transfer mode is controlled to spray transfer with less spatter. is there.

  Further, in the present invention, in order to stably control the droplet transfer form by spray transfer, that is, to stabilize the arc and not to deteriorate the welding quality, the inertness at the external gas nozzle is based on the jet theory. The gas injection conditions are set appropriately to ensure that the injected inert gas crosses the main shield gas and reaches the arc portion.

FIG. 1 is a schematic configuration diagram of a gas shield welding apparatus according to the present invention.
As shown in FIG. 1, the gas shield welding apparatus according to the present invention has a welding wire 2 for welding a base material 1, and a welding torch 3 for supporting the welding wire 2 is 3 with respect to the base material 1. The position is controlled so as to be movable in the dimension direction. In the welding torch 3, the welding wire 2 is fed from the wire feeding device 4, and the CO ₂ gas (first gas) for shielding the molten pool of the base material 1 from the atmosphere is the tip of the welding torch 3. It is supplied through a main nozzle provided in The CO ₂ gas is supplied from a carbon dioxide gas cylinder 7 via a pressure reducing valve / flow meter 5 and an electromagnetic valve 6.

Further, in the present invention, one or a plurality of additive gas nozzles (external nozzles) 8 are provided in the vicinity of the outside of the welding torch 3, and an inert gas (second gas) having a composition different from that of the CO ₂ gas is provided from the additive gas nozzle 8. ) Is injected into the CO ₂ gas. The inert gas is supplied from an inert gas cylinder 11 via a pressure reducing valve / flow meter 9 and a solenoid valve 10. As the inert gas, Ar, He or the like is used, but a _binary or ternary mixed gas obtained by adding CO ₂ , O ₂ or the like to an inert gas such as Ar or He may be used (hereinafter, referred to as “inert gas”). These gases are also called inert gases.) When a plurality of additive gas nozzles 8 are provided, the same type of inert gas may be injected, or different types of inert gases may be injected.

  Further, the additive gas nozzle 8 is provided with a CCD camera (arc position detecting means) 12, the position of the arc is grasped by image analysis by the CCD camera 12, and a nozzle position control device (nozzle position control means) 13 is used. Thus, the injection direction of the additive gas nozzle 8 (the angle of the additive gas nozzle 8, the three-dimensional position, etc.) is controlled in the arc direction so that the arc portion is in an optimum gas shield state. As a target direction of the additive gas nozzle 8, it is desirable that the central axis of the additive gas nozzle 8 is generally directed to the arc generation point at the tip of the welding wire 2 from a position where the arc portion is desired from above. As the arc position detection means, in addition to the CCD camera, a luminance sensor using light, a temperature sensor using heat, or the like may be used. At this time, the flow rate of the inert gas may be adjusted according to the welding conditions.

  Further, when there is no significant change in the welding conditions, the aiming direction of the additive gas nozzle 8 is also not significantly changed. Therefore, the welding torch 3 and additive gas nozzle 8 are configured integrally and the nozzle position control device 13 is omitted. It is good.

  The controlled devices such as the wire feeding device 4, the electromagnetic valves 6 and 10, and the nozzle position control device 13 are appropriately controlled by the control device 14 and generate an arc between the base material 1 and the welding wire 2. The welding power source 15 is also subjected to current control and the like by the control device 14, and gas shield welding is performed after the above two systems of gas flows are in a steady state.

FIG. 2 is a diagram for explaining a shield state during welding in the gas shield welding apparatus according to the present invention.
As shown in FIG. 2, in the gas shield welding apparatus according to the present invention, carbon dioxide gas 20 is allowed to flow from the main nozzle 3 a at the tip of the welding torch 3 during welding and an inert gas 21 is added to the arc 22 toward the arc 22. By injecting from 8, the arc 22 is gas shielded by the inert gas 21 and is in a spray transfer state to form an appropriate droplet 23. In addition, gas shielding is performed with the carbon dioxide gas 20 including the molten pool 24 around the arc 22 to prevent oxynitridation by the atmosphere. In the gas shield welding apparatus according to the present invention, as a method of injecting the inert gas 21 to the arc 22 portion, a small additive gas nozzle 8 is provided outside the main nozzle 3a on a different axis from the main nozzle 3a. A method of injecting an inert gas 21 to the arc 22 so as to cross the flow of the carbon dioxide gas 20 as the shielding gas was adopted. This is because providing a nozzle outside the welding torch 3 has a simpler structure and is more practical in terms of maintenance. Further, the tip of the additive gas nozzle 8 is disposed at the position of the tip of the main nozzle 3a of the welding torch 3 and is disposed at a position slightly inside from the boundary between the flow of the carbon dioxide gas 20 and the atmosphere so that the atmosphere is involved. Is to prevent as much as possible.

  With the above configuration, the same carbon dioxide gas 20 as that in the conventional case can be used for the shield of the molten pool 24 that requires a large amount of gas, and only the portion of the arc 22 that affects the droplet transfer is localized. Inert gas 21 can be injected to control the droplet transfer mode to spray transfer. When an inert gas such as Ar is used as the shielding gas, the inert gas such as Ar has a low arc potential gradient and a low concentration of poles, so that anode points are formed on the entire tip of the welding wire 2. As a result, the droplets 23 are transferred in small particles, so-called spray transfer, and almost no spatter is generated.

Here, the flow rate of the inert gas 21 used in the above configuration was estimated. Specifically, in order to quantitatively set the flow rate of the inert gas 21, the flow rate of the inert gas 21 necessary for controlling the atmosphere of the arc 22 portion was estimated. In FIG. 2, assuming that the inner diameter of the main nozzle 3a is a and the arc diameter on the surface of the base material is b, a cylindrical shield gas flow having a uniform flow velocity under the main nozzle 3a is assumed, and the flow rate flowing in the range equal to the arc diameter b is The flow rate of the necessary inert gas 21 is considered. If the area of the circle equal to the inner diameter of the main nozzle 3a is Sn and the area of the arc part is Sa,
Sn = πa ^2/4
Sa = πb ^2/4
Assuming that the total gas flow rate is c, the flow rate Qa of the inert gas 21 required for the arc portion is as follows based on the ratio of the above areas.
Qa = c × Sa / Sn
Usually, the flow rate of the total gas is about c = 20 L / min, the inner diameter of the main nozzle 3a is a = 20 mm, and the arc diameter on the surface of the base material is b = 7 mm. Therefore, when this condition is applied to the above equation, at least If the inert gas 21 of about 2.5 L / min is supplied to the arc 22, the droplet transfer mode can be appropriately controlled in the gas shield welding apparatus according to the present invention. If the amount of the inert gas 21 used is a small amount of about several L / min, the cost increase with respect to the conventional carbon dioxide welding method is small. Further, the upper limit of the usage amount of the inert gas 21 is preferably about 1/4 or less of the total gas flow rate, that is, 5 L / min or less from the viewpoint of cost.

Next, the setting of the inert gas injection condition will be described below with reference to FIGS. 3 and 4 based on the jet theory. In the gas shield welding apparatus of the present invention, in order to reliably control the droplet transfer mode to spray transfer, it is necessary to appropriately set the inert gas injection conditions.
FIG. 3A is a diagram for explaining a potential core, and FIG. 3B is a graph showing a ratio of potential core length / nozzle inner diameter to flow rate ratio.

The flow of the inert gas in the external nozzle system can be considered as a phenomenon in which the inert gas that becomes a jet flows in a form that crosses the flow of the main shield gas that becomes a cross wind.
If the flow direction of the cross wind U ₁ is the x-axis and the flow direction of the jet flow U ₀ is the y-axis, the potential core extends over a certain length from the jet nozzle outlet (AB) in the jet flow U ₀ receiving the cross wind U _1. There are (a-C-B) and region I called, in this region I, the gas exiting the nozzle outlet (a-B) may penetrate the crosswind U ₁ with less of deflection and concentration diffusion by crosswind U ₁ (See FIG. 3A). That is, in FIG. 2, if a potential core length equal to or greater than the distance from the tip of the additive gas nozzle 8 to the arc 22 is obtained, the inert gas 21 can be stably supplied to the arc 22. In FIG. 3A, a region II is a maximum deflection region that is deflected by the cross wind U ₁ , and a region III is a vortex region that is diffused by the cross wind U ₁ . In these regions II and III, it is difficult to stably supply the inert gas 21 to the arc 22. The line segment AD represents the outer boundary of the jet, the line segment BE represents the inner boundary of the jet, the line segment OG represents the center line of the jet, and the potential core region expands and contracts along the jet axis OF depending on the injection conditions.

Here, the additive gas nozzle inner diameter is d, the flow velocity ratio of the jet U ₀ to the cross wind U ₁ is α, and the potential core length ξ is the ratio of the additive gas nozzle inner diameter d, and is shown in the graph of FIG. From the graph of FIG. 3B, it can be seen that the length ξ of the potential core depends on the “flow velocity ratio α between the cross wind U ₁ and the jet U ₀ ” and the “added gas nozzle inner diameter d”. Here, in FIG. 3B, the black circle graph indicates the case where the additive gas nozzle inner diameter d is large, the white circle graph indicates the case where the additive gas nozzle inner diameter d is small, and the triangular graph indicates the case where the additive gas nozzle inner diameter d is intermediate between them. . In the graph of FIG. 3B, when the relationship between these parameters is approximated by a general function in the range of α = 5 to 10, the following equation is obtained.
ξ = 1.3d ・ α ^1/2 (1)

FIG. 4A shows the result of calculating the potential core length ξ using the above equation (1) and using the flow velocity ratio α between the cross wind U ₁ and the jet flow U _{0 and} the inner diameter d of the additive gas nozzle as parameters. Here, assuming that the diameter of the standard main nozzle is D, the calculation was performed for the case where the additive gas nozzle inner diameter d = 1/10 D, 1/7 D, and 1/5 D. If the radius of the main nozzle is 1 / 2D, that is, 1 / 2D, which is the distance from the end of the main nozzle to the arc, is the required potential core length, the additive gas nozzle inner diameter d = 1 / 7D and the flow rate ratio is 6.5. In the above case, it can be seen that the required potential core length ½D can be obtained.

  Furthermore, in the standard condition cross wind flow rate, that is, the standard flow rate of the main shield gas (for example, when the main nozzle inner diameter = 20 mm and the main shield gas flow rate = 20 L / min, the standard flow rate of the main shield gas = 1.1 m / s), the result of calculating the flow rate of the inert gas (jet flow rate) with the flow rate ratio α and the additive gas nozzle inner diameter d as parameters is the graph shown in FIG. 4B. It can be seen that when the additive gas nozzle inner diameter d = 1 / 7D and the flow rate ratio is 5.5 or more, the gas flow rate of 2.5 L / min or more necessary for the droplet transfer mode is satisfied. From the viewpoint of cost, it is desirable that the effects of the present invention can be obtained with as little inert gas flow as possible. For this purpose, the inner diameter of the additive gas nozzle should be reduced to a relatively high flow rate ratio. However, if the nozzle inner diameter is too small or the flow rate ratio is too large, the potential core region may be narrow or the atmosphere may be engulfed. The gas shield may be insufficient. Accordingly, when considering the case where the inner diameter of the main nozzle is as small as about 11 mm, the lower limit of the inner diameter d of the additive gas nozzle needs to be at least 1 / 10D or more. Further, the upper limit of the inner diameter d of the additive gas nozzle may be larger, but if the lower limit flow rate ratio for forming the potential core is 5, the required flow rate of the inert gas increases as the inner diameter increases. In consideration of the consumption of inert gas, an inner diameter of about 1 / 4D is desirable.

  From the above calculation, the inert gas injection conditions include both the required potential core length and the required inert gas flow rate when the additive gas nozzle inner diameter d = 1 / 7D and the gas flow rate ratio α = 6.5 or more. Satisfied. Thus, the effect of reducing spatter in the gas shield welding apparatus according to the present invention was verified using an additive gas nozzle having an inner diameter of 1 / 7D.

In the verification experiment, downward welding was performed using high-strength steel as a base material in the gas shield welding apparatus shown in FIG. The main experimental condition was that carbon dioxide arc welding was performed in a large current region of 280 to 300 A where spattering was remarkable. The flow rate of the main shield gas was fixed at a constant flow rate condition so that the influence of gas addition could be easily understood. As the inert gas, a binary gas of 95% Ar-5% CO ₂ was selected so that the influence of the gas addition could be easily understood. This is because, in the MAG welding method using Ar—CO ₂ binary gas as a shielding gas, it is known that a remarkable sputter reduction effect can be obtained when the Ar ratio is 80% or more, particularly 95% Ar. This is because, in the case of the condition of −5% CO ₂ , the penetration form, current waveform, and arc form are significantly different from those in the case of 100% CO ₂ . The tip of the additive gas nozzle was positioned so as to be located at the tip of the main nozzle, the target position was slightly above the anode point at the tip of the welding wire, and the angle with respect to the surface of the base material was 40 °. Under the above experimental conditions, the effects on the arc form, droplet transfer form, and spatter generation were examined.

FIG. 5 shows the results of measuring the spatter amount adhering to the nozzle with respect to the flow rate ratio. When a binary gas of 95% Ar-5% CO ₂ was injected into the arc, no significant effect was seen under the condition of the flow rate ratio = 1, but the current waveform and arc under the condition of the flow rate ratio = 2. -Changes in the droplet transfer form began to appear, and a remarkable sputter reduction effect was confirmed at a flow rate ratio of 2.5 to 4. In this case, the unevenness of the current waveform is reduced, the arc shape is a wide cone shape peculiar to spray transfer, no large droplets are seen at the tip of the welding wire, and the penetration form into the base metal is also a bead peculiar to spray transfer. The central part was a deep wine cup-shaped melt. The amount of spatter generated is the smallest when the flow rate ratio = 3, and is reduced to about 1/6 compared with conventional carbon dioxide welding. When the flow rate ratio was further increased and the flow rate ratio was set to 12, a shielding failure occurred and a blow hole was generated. This is thought to be because the air entrainment increased and a good shield state could not be maintained. From the above verification experiment, it was found that the flow rate ratio = 2.5 to 4, particularly 3 is the best condition, the lower limit is the flow rate ratio = 2, and the upper limit is the flow rate ratio = 12. When the flow rate ratio is converted into the flow rate of the inert gas, this result agrees well with the calculated value of the flow rate of the inert gas that satisfies the required potential core length shown in FIG.

Next, to verify the effect of the gas composition in the binary gas Ar-CO _2.
95% Ar-5% CO2 _binary gas is a commercial product, but it is a little special, and it is obtained in comparison with Ar + 10-20% CO2 _binary gas, which is often used in normal MAG welding. Hateful. Therefore, a verification experiment was conducted to grasp the CO ₂ ratio at which the effect of the present invention was obtained in the Ar—CO ₂ binary gas. The flow rate of the inert gas is fixed at a flow rate condition that is most effective in the binary system gas of 95% Ar-5% CO ₂ , and each gas flow rate is changed so that the CO ₂ ratio with respect to Ar changes. A verification experiment was conducted. The result is the graph shown in FIG. When the ratio of CO _{2 to} Ar is 15 to 20%, spray transfer does not occur and the amount of spatter adhesion is large, but when the ratio of CO _{2 to} Ar is 10%, spray transfer can be achieved and the amount of spatter adhesion Was also reduced. As shown in the graph of FIG. 6, it can be seen that when the CO ₂ ratio to Ar is 5 to 10%, the effect of reducing the sputtering is remarkably obtained.

In this verification experiment, it was found that the amount of spatter generated can be reduced to 1/6 of the conventional method. In this case, the post-treatment man-hour reduction effect was estimated.
The following two items were considered as the man-hour reduction items.
1) Man-hour for removing spatter adhering to nozzle 2) Man-hour for removing spatter adhering to product For item 1), the man-hour is reduced to 1/6 in proportion to the amount of spatter generated. With respect to the item ()), since the work target area is the same, the work man-hour is not necessarily proportional to the amount of spatter, but assuming that the work man-hour reduction time is reduced to about 1/2, The possibility of significant man-hour reduction corresponding to ~ 30% was confirmed.

1 is a schematic configuration diagram of a gas shield welding apparatus according to the present invention. It is a figure explaining the shield state during welding in the gas shield welding apparatus concerning the present invention. FIG. 4 is a diagram illustrating a potential core and a graph showing a ratio of potential core length / nozzle inner diameter to flow velocity ratio. In the gas shield welding device concerning the present invention, it is a graph of potential core length and inert gas flow rate to flow rate ratio. It is a graph of the flow rate ratio and spatter adhesion amount in the gas shield welding apparatus which concerns on this invention. It is a graph of the inert gas density | concentration and sputter | spatter adhesion amount in the gas shield welding apparatus which concerns on this invention. It is a figure explaining the shield state during welding in the conventional gas shield welding apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base material 2 Welding wire 3 Welding torch 3a Main nozzle 4 Wire feeder 5 Pressure reducing valve / flow meter 6 Electromagnetic valve 7 Carbon dioxide gas cylinder 8 Additive gas nozzle 9 Pressure reducing valve / flow meter 10 Electromagnetic valve 11 Inert gas cylinder 12 CCD camera 13 Nozzle Position control device 14 Control device 15 Welding power source 20 Carbon dioxide gas 21 Inert gas 22 Arc region 23 Droplet 24 Molten pool

Claims (12)

Using the main nozzle provided at the tip of the welding torch, while flowing the first gas that protects the molten pool from the atmosphere,
Using one or more external nozzles provided outside the welding torch, a second gas having a composition different from that of the first gas is directed toward an arc portion formed at the tip of the welding torch. A gas shield welding method characterized by spraying. The gas shield welding method according to claim 1,
The gas shield welding method, wherein the second gas is injected from the external nozzle so that the arc portion is included in at least a potential core region formed by the second gas. In the gas shield welding method according to claim 2,
A gas shield welding method characterized in that an inner diameter of 1/10 or more of the inner diameter of the main nozzle is used as the external nozzle. In the gas shield welding method according to claim 2 or 3,
A gas shield welding method, wherein a flow rate of the second gas injected from the external nozzle is in a range of 2 to 12 times a flow rate of the first gas flowing from the main nozzle. In the gas shield welding method according to any one of claims 2 to 4,
A gas shield welding method, wherein a flow rate of the second gas injected from the external nozzle is 5 L / min or less. In the gas shield welding method according to any one of claims 1 to 5,
Using the arc position detection means for detecting the position of the arc part, detecting the position of the arc part,
Gas shield welding characterized in that the second gas injection direction is controlled based on position information detected by the arc position detection means using nozzle position control means for controlling the arrangement position of the external nozzle. Method. A welding torch having a main nozzle for flowing a first gas protecting the molten pool from the atmosphere;
One or a plurality of external nozzles that are provided outside the welding torch and inject a second gas having a composition different from that of the first gas toward an arc portion formed at a tip of the welding torch;
A gas shield welding apparatus comprising: The gas shield welding apparatus according to claim 7,
The gas shield welding apparatus according to claim 1, wherein the second gas injection condition is set by the external nozzle so that the arc portion is included in at least a potential core region formed by the second gas. The gas shield welding apparatus according to claim 8,
The gas shield welding apparatus according to claim 1, wherein an inner diameter of the external nozzle is 1/10 or more of an inner diameter of the main nozzle. In the gas shield welding apparatus according to claim 8 or 9,
The gas shield welding apparatus, wherein a flow rate of the second gas injected from the external nozzle is in a range of 2 to 12 times a flow rate of the first gas flowing from the main nozzle. In the gas shield welding apparatus according to any one of claims 8 to 10,
The gas shield welding apparatus, wherein a flow rate of the second gas injected from the external nozzle is 5 L / min or less. In the gas shield welding apparatus according to any one of claims 7 to 11,
Arc position detection means for detecting the position of the arc portion;
Nozzle position control means for controlling the arrangement position of the external nozzle based on the position information of the arc portion detected by the arc position detection means to control the injection direction of the second gas;
A gas shield welding apparatus comprising:

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