JP2008229705A - Plasma gma welding torch and plasma gma welding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma GMA welding torch and a plasma GMA welding method by which plasma GMA welding is smoothly started and by which a superior weld bead can be formed. <P>SOLUTION: The plasma GMA welding torch A1 is equipped with a contact tip 1 for supporting a wire W that is fed along the center axis by a wire feeding means 7, a plasma electrode 2 that is arranged coaxially in the manner surrounding the contact tip 1, and a shield nozzle 4 that is arranged coaxially in the manner surrounding the plasma electrode 2. The tip end of the plasma electrode 2 is located in the front in the wire W feeding direction relative to the tip end of the contact tip 1. A distance h between the tip end of the plasma electrode 2 and that of the contact tip 1 is 4.1-7.5 times the diameter of the wire W. With this structure, weld bead disturbance due to bend of the wire W is eliminated and also the ignition probability of the plasma arc can be made extremely high. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a plasma GMA welding torch and a plasma GMA welding method.

  FIG. 5 shows an example of a welding apparatus used for conventional plasma GMA welding (see, for example, Patent Document 1). The welding apparatus Y shown in the figure includes a welding torch X, a plasma power supply 94, a GMA power supply 95, a wire supply means 96, and a gas cylinder 97. A wire W is supplied from the wire supply means 96. The wire W is sent out along the central axis of the welding torch X. The welding torch X has a contact tip 91, a plasma electrode 92, and a shield nozzle 93.

  The contact chip 91 supports the wire W. The plasma electrode 92 surrounds the contact chip 91 and is disposed on the concentric axis with the contact chip 91. An inert gas is supplied as a plasma gas from a gas cylinder 97 to the gap between the contact tip 91 and the plasma electrode 92. The shield nozzle 93 surrounds the plasma electrode 92 and is disposed on the concentric axis with the plasma electrode 92. An inert gas is supplied as a shield gas from a gas cylinder 97 to the gap between the plasma electrode 92 and the shield nozzle 93.

  The plasma power source 94 is a power source for generating a plasma arc by applying a voltage between the plasma electrode 92 and the welding target material P. The GMA power source 95 is for generating a GMA arc by applying a voltage for generating an arc from the wire W.

  The advantage of welding by the welding apparatus Y is that plasma welding and GMA welding are simultaneously performed on the same portion of the welding target material P. That is, a part of the welding target material P is in a molten state by ejecting a plasma arc generated by converting the plasma gas into plasma. A droplet of the wire W is supplied to the melted portion. Thereby, compared with the case where the welding target material P is welded only by GMA welding, for example, it can weld more reliably. Further, the GMA arc generated by the voltage application from the GMA power source 95 is included in the plasma gas that has been converted into plasma. This is advantageous for stabilizing the behavior of the GMA arc. In addition to the above, the following matters can be cited as advantages of welding by the welding apparatus Y. Due to the presence of the plasma arc, the surface tension of the droplet at the tip of the wire W is lowered. For this reason, the droplet breakage from the wire W is improved. Further, the melting of the wire W is promoted by the plasma arc. As a result, more wires W can be melted without increasing the current from the GMA power source 95, which is suitable for high-efficiency welding. Further, in addition to the shielding gas Gs, the GMA arc and the welded part are shielded by the plasma arc. Thereby, it can prevent that an impurity is taken in into a welding part. Furthermore, the effect of restraining the GMA arc by the plasma arc can be expected.

  However, welding with the welding apparatus Y has the following problems.

  First, the welding defect resulting from the bending of the wire W occurs. That is, the wire W is generally stretched from the wound state and fed to the welding torch X. Depending on the degree of bending remaining on the wire W, the wire W is largely displaced from the central axis of the plasma electrode 92 and the shield nozzle 93. For this reason, the GMA arc is deviated from the center of the plasma arc. As a result, the deepest part of the weld bead may be offset from the center of the bead or undercut may occur, resulting in poor welding.

  On the other hand, the GMA arc generation location where the GMA arc is generated from the wire W is positioned so that the feeding speed of the wire W and the current value from the GMA power source 95 are balanced. For this reason, if these conditions are constant, the distance between the GMA arc occurrence point and the tip of the contact tip 91 does not change greatly. Here, a configuration in which only the contact tip 91 is brought close to the welding target material P when the positional relationship between the welding target material P and the plasma electrode 92 is constant will be considered. The portion where the GMA arc is generated moves toward the welding target material P as much as the contact tip 91 is brought closer. For this reason, the distance between the plasma electrode 92 and the GMA arc occurrence location becomes relatively large. Since the GMA arc induces a plasma arc, such a configuration has a problem that the plasma arc cannot be reliably ignited.

  Further, in the welding torch X, the shield nozzle 93 plays a role of restricting the plasma arc. Since the shield nozzle 93 is not generally made into a water cooling structure, it may become high temperature. With such a shield nozzle 93, the plasma arc could not be sufficiently narrowed, causing a lack of penetration depth. In order to narrow the plasma arc by the shield nozzle 93, it is advantageous to reduce the diameter of the tip opening of the shield nozzle 93. However, if the tip opening is made too small, the dynamic pressure of the plasma gas becomes unreasonably high. This is disadvantageous for firing the GMA arc. Further, if the flow rates of the plasma gas and the shield gas are not sufficient, the penetration depth becomes insufficient.

JP 63-168283 A

  The present invention has been conceived under the circumstances described above, and is capable of smoothly starting plasma GMA welding and forming a good weld bead and a plasma GMA welding method. The issue is to provide

  The welding torch provided by the first aspect of the present invention includes a contact tip for supporting a wire fed along a central axis by a wire supply means, and a plasma electrode disposed on a concentric axis so as to surround the contact tip And a shield nozzle arranged on a concentric shaft so as to surround the plasma electrode, wherein the tip of the plasma electrode has a wire feeding direction that is more than the tip of the contact tip The distance between the tip of the plasma electrode and the tip of the contact tip is 4.1 to 7.5 times the diameter of the wire.

  According to such a structure, the said wire can be appropriately arrange | positioned on the center axis | shaft of the said welding torch because the said distance is 7.5 times or less of the diameter of the said wire. Thereby, the favorable weld bead which the deepest part is located in the center can be formed. Further, when the distance is 4.1 times or more of the diameter of the wire, the ignition probability of the plasma arc can be almost 100%, and plasma GMA welding can be started smoothly.

The plasma GMA welding method provided by the second aspect of the present invention is arranged on a concentric shaft so as to surround the contact tip, which supports the wire fed along the central axis by the wire supply means. A plasma GMA welding torch comprising a plasma electrode and a shield nozzle disposed on a concentric axis so as to surround the plasma electrode; a gas supply means for supplying gas to the plasma GMA welding torch; and the contact tip and the weld A plasma GMA welding method using a GMA power source for applying a voltage between a target material and a plasma power source for applying a voltage between the plasma electrode and a material to be welded, the plasma electrode and the shield nozzle A plasma nozzle disposed on a concentric axis between the plasma electrode and the plasma electrode. The diameter of the end opening is 3.3 to 5.9 times the diameter of the wire, and the tip opening of the plasma nozzle has a diameter equal to or greater than the diameter of the tip opening of the plasma electrode, The gas supply means has a center gas in the gap between the contact tip and the plasma electrode, and a plasma gas in the gap between the plasma electrode and the plasma nozzle. An inert gas is supplied as a shielding gas to the gap between the plasma nozzle and the shield nozzle, and the flow rate density obtained by dividing the total flow rate of the center gas and the plasma gas by the tip opening area of the plasma nozzle is 0. .39L / (mm ² min) or more.

  According to such a configuration, the center gas and the plasma gas can be discharged in a sufficiently throttled state without unduly spreading the plasma gas and the plasma nozzle. Further, the plasma nozzle can be appropriately contracted by the plasma nozzle. Furthermore, by setting the flow density of the center gas and the plasma gas in the above range, it is possible to increase the dynamic pressure when the center gas and the plasma gas are discharged, and to deepen the penetration depth. It is suitable for.

  Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

  Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the drawings.

  FIG. 1 shows an example of a welding apparatus using a GMA welding torch according to the first aspect of the present invention. The welding apparatus B1 of the present embodiment includes a welding torch A1, a plasma power source 5, a GMA power source 6, a wire supply means 7, and a gas cylinder 8. The welding apparatus B1 is configured to be able to simultaneously perform plasma welding and GMA welding on the same portion of the welding target material P.

  The welding torch A1 includes a contact tip 1, a plasma electrode 2, and a shield nozzle 4, and is configured to send out a wire W along its central axis.

  The contact chip 1 supports the wire W and makes the wire W and the GMA power source 6 conductive. The contact tip 1 is made of Cu or Cu alloy, and has a substantially cylindrical shape that defines the central axis of the welding torch A1. The inner diameter of the contact chip 1 is set to a size that allows sufficient conduction while allowing the wire W to be inserted. In the present embodiment, the diameter of the wire W is 1.2 mm.

  The plasma electrode 2 is for applying a voltage from the plasma power source 5, and is made of, for example, Cu or Cu alloy. The plasma electrode 2 is disposed on a concentric axis so as to surround the contact chip 1 and has a substantially cylindrical shape. A gap is provided between the plasma electrode 2 and the contact tip 1. Moreover, the plasma electrode 2 is indirectly water-cooled by a channel for passing cooling water provided outside the figure.

  A plasma gas Gp is supplied from the gas cylinder 8 into the gap between the contact tip 1 and the plasma electrode 2. The plasma gas Gp is an inert gas such as Ar gas, for example. The plasma gas Gp supplied to the gap between the contact tip 1 and the plasma electrode 2 is ejected from the tip of the welding torch A1.

  The shield nozzle 4 is for defining the jet direction of the shield gas Gs. The shield nozzle 4 is disposed on a concentric axis so as to surround the plasma electrode 2 and has a substantially cylindrical shape. A gap is provided between the shield nozzle 4 and the plasma electrode 2.

  In the gap between the plasma electrode 2 and the shield nozzle 4, an inert gas such as Ar gas is supplied as the shield gas Gs from the gas cylinder 8. This shield gas Gs is for preventing the welded portion from being oxidized. The shield gas Gs supplied to the gap between the plasma electrode 2 and the shield nozzle 4 is ejected by the shield nozzle 4 so as not to spread from the central axis of the welding torch A1.

  In the present embodiment, the distance h between the tip of the contact chip 1 and the tip of the plasma electrode 2 is 5 to 9 mm. This is intended to achieve the effects of the present invention described later, and is meaningful in that the distance h is 4.1 to 7.5 times the diameter of the wire W.

  The plasma power source 5 is a power source for supplying power necessary for generating a plasma arc by converting the plasma gas Gp into plasma. The plasma power source 5 is a DC power source, and for example, its anode is connected to the plasma electrode 2 and its cathode is connected to the material P to be welded.

  The GMA power source 6 is a power source for supplying electric power necessary for generating a GMA arc between the wire W and the welding target material P. The GMA power source 6 is a DC power source, and for example, its anode is connected to the contact chip 1 and its cathode is connected to the material P to be welded.

  The wire supply means 7 is for supplying the wire W toward the welding torch A1. In the present embodiment, the wire supply means 7 includes a motor (not shown) and a pair of rollers driven by this motor. The supply speed of the wire W by the wire supply means 7 can be controlled according to the input power by the plasma power supply 5 and the GMA power supply 6. As a material of the wire W, for example, Fe, Al or the like may be used.

  Next, the operation of the welding torch A1 will be described.

  According to the present embodiment, it is possible to prevent the occurrence of poor welding due to the bending of the wire W. In the welding torch A1, the distance h between the tip of the contact tip 1 and the tip of the plasma electrode 2 is 5 to 9 mm. As shown in FIG. 2, the misalignment of the wire W due to the bending of the wire W becomes significant in the range where the distance h exceeds 9 mm. For this reason, the deepest part of a weld bead will remove from the center of a weld bead. On the other hand, if the distance h is 9 mm or less, the wire W can be appropriately disposed on the central axis of the welding torch A1. Thereby, the favorable weld bead which the deepest part is located in the center can be formed.

  Moreover, according to this embodiment, a plasma arc can be reliably started. As shown in FIG. 2, when the distance h is less than 5 mm, the ignition probability Pr of the plasma arc is generally less than 50%. As described in the description of the prior art, when the tip of the contact tip 1 is relatively brought close to the welding target material P, the distance between the tip of the plasma electrode 2 and the GMA arc occurrence position of the wire W is relatively This is considered to be caused by becoming too large. If the ignition of the plasma arc fails, the plasma GMA welding cannot be started properly. On the other hand, when the distance h is in the range of 5 mm or more, the contact tip 1 is positioned away from the welding target material P with respect to the plasma electrode 2. For this reason, the GMA arc generation location of the wire W is brought close to the plasma electrode 2 so as to be at an appropriate position. As a result, the ignition probability Pr is almost 100%. Therefore, the plasma arc can be reliably ignited and plasma GMA welding can be started smoothly.

  As described above, by setting the distance h to 5 to 9 mm, it is possible to reliably perform the ignition of the plasma arc while forming a good weld bead. As a condition for exhibiting such an action, the inventors have found that it is effective to set the distance h in an appropriate range with respect to the diameter of the wire W. Specifically, if the distance h is 4.1 to 7.5 times the diameter of the wire W, the above-described action can be achieved.

  FIG. 3 shows an example of a welding apparatus used in the GMA welding method according to the second aspect of the present invention. In these drawings, the same or similar elements as those in the above embodiment are denoted by the same reference numerals as those in the above embodiment.

  The welding apparatus B2 of the present embodiment includes a welding torch A2, a plasma power source 5, a GMA power source 6, a wire supply means 7, and a gas cylinder 8. The welding apparatus B2 is configured to be able to simultaneously perform plasma welding and GMA welding on the same portion of the welding target material P. As will be described later, the plasma GMA welding method of the present embodiment is classified as a plasma MIG welding method by supplying an inert gas such as Ar gas from a gas cylinder 8.

  The welding torch A2 includes a contact tip 1, a plasma electrode 2, a plasma nozzle 3, and a shield nozzle 4, and is configured to send out a wire W along its central axis.

  The contact chip 1 supports the wire W and makes the wire W and the GMA power source 6 conductive. The contact tip 1 is made of Cu or Cu alloy and has a substantially cylindrical shape that defines the central axis of the welding torch A. The inner diameter of the contact chip 1 is set to a size that allows sufficient conduction while allowing the wire W to be inserted. In the present embodiment, the diameter of the wire W is 1.2 mm.

  The plasma electrode 2 is for applying a voltage from the plasma power source 5, and is made of, for example, Cu or Cu alloy. The plasma electrode 2 is disposed on a concentric axis so as to surround the contact chip 1 and has a substantially cylindrical shape. A gap is provided between the plasma electrode 2 and the contact tip 1. Moreover, the plasma electrode 2 is indirectly water-cooled by a channel for passing cooling water provided outside the figure. In the present embodiment, the diameter d1 of the tip opening 2a of the plasma electrode 2 is 4 to 7 mm. This is intended to achieve the effects of the present invention described later, and is meaningful in that the diameter d1 is 3.3 to 5.9 times the diameter of the wire W.

  A center gas Gc is supplied from the gas cylinder 8 into the gap between the contact tip 1 and the plasma electrode 2. The center gas Gc is an inert gas such as Ar gas, for example. The center gas Gc supplied to the gap between the contact tip 1 and the plasma electrode 2 is ejected from the tip of the welding torch A through the tip opening 2a.

  The plasma nozzle 3 is for constricting the GMA arc and the plasma arc, and is made of, for example, Cu or Cu alloy. The plasma nozzle 3 is disposed on a concentric axis so as to surround the plasma electrode 2 and has a substantially cylindrical shape. The plasma nozzle 3 is formed with a channel for allowing cooling water to pass therethrough and is directly cooled by water. The tip of the plasma nozzle 3 is located in front of the tip of the plasma electrode 2 in the wire W feeding direction. In the present embodiment, the diameter d2 of the tip opening 3a of the plasma nozzle 3 is 7 to 9 mm. This is intended to achieve the effects of the present invention described later, and is meaningful in that the diameter d2 is 5.8 to 7.5 times the diameter of the wire W.

  In the gap between the plasma electrode 2 and the plasma nozzle 3, an inert gas such as Ar gas is supplied as a plasma gas Gp from the gas cylinder 8. This plasma gas Gp is for constricting the plasma arc. The plasma gas Gp supplied to the gap between the plasma electrode 2 and the plasma nozzle 3 is ejected from the tip of the welding torch A2 through the tip opening 3a.

  The shield nozzle 4 is for defining the jet direction of the shield gas Gs. The shield nozzle 4 is disposed on a concentric axis so as to surround the plasma nozzle 3 and has a substantially cylindrical shape. A gap is provided between the shield nozzle 4 and the plasma nozzle 3.

  In the gap between the plasma nozzle 3 and the shield nozzle 4, an inert gas such as Ar gas is supplied as the shield gas Gs from the gas cylinder 8. This shield gas Gs is for preventing the welded portion from being oxidized. The shield gas Gs supplied to the gap between the plasma nozzle 3 and the shield nozzle 4 is ejected by the shield nozzle 4 so as not to spread significantly from the central axis of the welding torch A2.

  The plasma power source 5 is a power source for supplying power necessary for generating a plasma arc by converting the center gas Gc into plasma. The plasma power source 5 is a DC power source, and for example, its anode is connected to the plasma electrode 2 and its cathode is connected to the material P to be welded.

  The GMA power source 6 is a power source for supplying electric power necessary for generating a GMA arc between the wire W and the welding target material P. The GMA power source 6 is a DC power source, and for example, its anode is connected to the contact chip 1 and its cathode is connected to the material P to be welded.

  The wire supply means 7 is for supplying the wire W toward the welding torch A2. In the present embodiment, the wire supply means 7 includes a motor (not shown) and a pair of rollers driven by this motor. The supply speed of the wire W by the wire supply means 7 can be controlled according to the input power by the plasma power supply 5 and the GMA power supply 6. As a material of the wire W, for example, Fe, Al or the like may be used.

In the GMA welding method using the welding apparatus B2, the total flow rate of the center gas Gc and the plasma gas Gp is set to 25 L / min or more. This is intended to achieve the effects of the present invention to be described later, and the flow density obtained by dividing the flow rate by the area of the tip opening 3a of the plasma nozzle 3 is 0.39 L / (mm ² · min) or more. There is significance in being. In order to achieve such a flow density, a flow rate adjusting means FC, for example, a float type flow meter with a needle valve or a mass flow controller is provided in the path for supplying an inert gas such as Ar gas from the gas cylinder 8. .

  Next, the operation of the GMA welding method according to the second aspect of the present invention will be described.

  FIG. 4 shows that the plasma gas from the plasma power source 5 is 150 A, the consumable electrode current from the GMA power source 6 is a pulse current having an average of about 250 A, and the center gas Gc and plasma gas Gp are Indicates the penetration depth dp when the flow rate Q is changed. As understood from the figure, in the range where the flow rate Q is less than 25 L / min, the penetration depth dp is significantly less than 5 mm. On the other hand, in the range where the flow rate Q is 25 L / min or more, the penetration depth dp is 5 mm or more, and the penetration depth dp tends to increase as the flow rate Q increases.

  As a reason for this, the inventors have found a relationship between the magnitude of the flow rate Q and the diameters of the tip opening 2 a of the plasma electrode 2 and the tip opening 3 a of the plasma nozzle 3. First, by setting the diameter d1 of the tip opening 2a of the plasma electrode 2 to 4 to 7 mm, it is possible to discharge the center gas Gc so as not to spread from the wire W while enclosing the wire W. Next, the diameter d2 of the tip opening 3a of the plasma nozzle 3 is set to 7 to 9 mm, so that the plasma gas Gp moderately controls the center gas Gc without unduly disturbing the center gas Gc discharged along the wire W. It is discharged to squeeze. Furthermore, since the plasma nozzle 3 that is directly water-cooled by the cooling water in the channel is kept at a significantly low temperature during welding, the plasma arc can be appropriately contracted. In order to achieve such an effect, it is preferable that the diameter d1 is 3.3 to 5.9 times the diameter of the wire W and the diameter d2 is 5.8 to 7.5 times the diameter of the wire W. .

In addition, an appropriate penetration depth can be obtained by increasing the dynamic pressure of the center gas Gc and the plasma gas Gp. In order to increase the dynamic pressure, it is preferable that the flow rate density obtained by dividing the flow rate Q by the area of the tip opening 3a of the plasma nozzle 3 is preferably 0.39 L / (mm ² · min) or more. These studies revealed that.

  The plasma GMA welding torch and the plasma GMA welding method according to the present invention are not limited to the above-described embodiments. The specific configuration of the plasma GMA welding torch and the plasma GMA welding method according to the present invention can be varied in design in various ways.

It is a system configuration figure showing an example of a welding device in which a welding torch concerning the 1st side of the present invention is used. It is a graph which shows the plasma arc ignition probability in GMA welding, and a weld bead cross section. It is a system block diagram which shows an example of the welding apparatus used for the welding method which concerns on the 2nd side surface of this invention. It is a graph which shows the relationship between the flow rate density and penetration depth in GMA welding. It is a system block diagram which shows an example of the conventional GMA welding apparatus.

Explanation of symbols

A1, A2 (GMA) welding torch B1, B2 welding equipment d2, d3 opening diameter Gc center gas Gp plasma gas Gs shield gas h distance between tips P material to be welded W wire 1 contact tip 2 plasma electrode 2a tip opening 3 plasma nozzle 3a Tip opening 4 Shield nozzle 5 Plasma power source 6 MGA power source 7 Wire supply means 8 Gas cylinder

Claims (2)

A contact tip that supports the wire fed along the central axis by the wire supply means;
A plasma electrode disposed on a concentric axis so as to surround the contact tip;
A shield nozzle disposed on a concentric axis so as to surround the plasma electrode;
A plasma GMA welding torch comprising:
The tip of the plasma electrode is positioned in front of the tip of the contact tip in the wire feeding direction, and the distance between the tip of the plasma electrode and the tip of the contact tip is 4 times the diameter of the wire. A welding apparatus characterized by having a magnification of 1 to 7.5. A contact tip that supports the wire fed along the central axis by the wire supply means;
A plasma electrode disposed on a concentric axis so as to surround the contact tip;
A shield nozzle disposed on a concentric axis so as to surround the plasma electrode;
A plasma GMA welding torch comprising:
Gas supply means for supplying gas to the plasma GMA welding torch;
A GMA power source for applying a voltage between the contact tip and the material to be welded;
A plasma power source for applying a voltage between the plasma electrode and the material to be welded;
A plasma GMA welding method using
A plasma nozzle disposed on a concentric axis between the plasma electrode and the shield nozzle;
The diameter of the tip opening of the plasma electrode is 3.3 to 5.9 times the diameter of the wire,
The tip opening of the plasma nozzle has a diameter equal to or larger than the diameter of the tip opening of the plasma electrode, and is 5.8 to 7.5 times the diameter of the wire,
The gas supply means includes a center gas in the gap between the contact tip and the plasma electrode, a plasma gas in the gap between the plasma electrode and the plasma nozzle, and a shield gas in the gap between the plasma nozzle and the shield nozzle. The flow rate density obtained by dividing the flow rate of supplying the active gas and totaling the center gas and the plasma gas by the tip opening area of the plasma nozzle is 0.39 L / (mm ² · min) or more. A plasma GMA welding method.

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