JP2010104996A - Plasma electrode and plasma mig welding torch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma MIG welding torch capable of obtaining beautiful weld beads. <P>SOLUTION: In the plasma MIG welding torch, a plasma electrode is installed coaxially with a power feed tip in which a welding wire is inserted. Plasma gas is supplied to a plasma nozzle surrounding the plasma electrode, with shield gas supplied to a shield nozzle surrounding the plasma nozzle. The plasma electrode is provided with a columnar shape having conductivity and is hollowly formed, with a wire insertion hole formed in the tip end face, and with a tip end face angle formed by the tip end face and a face orthogonal to the axial center. This tip end face angle is preliminarily determined at nearly the same angle as the drag angle of the plasma MIG welding torch. Consequently, if a workpiece is aluminum alloy, a cleaning width of plasma arc can be secured, preventing molten metal from being partly overheated. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a plasma electrode and a plasma MIG welding torch capable of obtaining a good weld bead.

  There has been proposed a plasma MIG welding method in which a MIG arc is generated while feeding a welding wire as a consumable electrode, and a plasma arc including the above MIG arc is generated using argon gas or the like as a plasma gas. (For example, refer to Patent Document 1). FIG. 7 is a configuration diagram of the plasma MIG welding torch 5 of the prior art. In the figure, the plasma welding power source PSP outputs a plasma arc current Iwp and a plasma arc voltage Vwp between the plasma electrode 8 and the workpiece 16. The plasma electrode 8 screwed to the torch body 23 is surrounded by a plasma nozzle 9, and the plasma gas 12 flows at high speed in the plasma nozzle 9, and a plasma arc 14 is generated between the workpiece 16 and the workpiece. The plasma nozzle 9 is for electrically constraining the plasma arc 14 and a MIG arc 15 described later, and is a conductive member that is directly or indirectly water-cooled.

  The plasma nozzle 9 is further surrounded by a shield nozzle 10, and a shield gas 13 flows through the shield nozzle 10. As the plasma electrode 8, a water-cooled copper electrode, a tungsten electrode or the like is used, and the inside has a hollow structure. In the figure, the plasma arc 14 is generated with an electrode positive polarity. The plasma arc 14 may have an electrode negative polarity.

  The MIG welding power source PSM outputs a wire feed control signal Fc that controls the rotation of the wire feed motor WM, and outputs a MIG arc current Iwm and a MIG arc voltage Vwm between the power feed tip 7 and the workpiece 16. The power supply tip 7 is formed with an insertion hole through which the welding wire 17 is inserted, and is provided coaxially in the plasma electrode 8. A center gas 11 flows in the plasma electrode 8.

  The welding wire 17 is fed by a feed roll 18 coupled to a wire feed motor WM. The welding wire 17 is fed in contact with the inside of the insertion hole of the power feed tip 7 to be fed and a mig arc 15 is generated between the welding wire 17 and the workpiece 16. The MIG arc 15 is generated by being included in the plasma arc 14. Therefore, the welding wire 17 is heated by the plasma arc 14 and the MIG arc 15 to transfer droplets. The MIG arc 15 is generated with an electrode positive polarity. The feeding speed of the welding wire 17 is Fw [m / min].

 When the center gas 11 and the plasma gas 12 pass through the narrow plasma nozzle 9, the pressure is increased, the thermal constraint between the plasma arc 14 and the MIG arc 15 is strengthened, and the concentration is increased.

  8A and 8B are diagrams showing a conventional plasma electrode, where FIG. 8A is a cross-sectional view, and FIG. 8B is a bottom view as seen from the front end side. As shown in the figure, the angle θ1 formed by the tip surface 8a of the conventional plasma electrode and the shaft core 1 is formed at a right angle. Further, a screw portion 26 is formed at the base end portion of the plasma electrode 8.

Japanese Utility Model Publication No. 62-10964

  In the case of general joint welding, in order to improve the shielding performance by leveling the welding bead, the plasma MIG welding torch is welded with a forward angle as shown in FIG. This angle is generally 10-15 degrees. FIG. 9 is a view showing a state in which welding is performed with a forward angle provided by using the plasma MIG welding torch 5 of the prior art, and FIG. 10 is a view showing a state in which an arc is generated. 9 and 10, the same functions as those of the conventional plasma MIG welding torch 5 shown in FIG.

  As shown in FIG. 9, when the advance angle α is provided in the plasma MIG welding torch 5, the distance between the tip of the plasma electrode 8 and the workpiece is compared between the welding progress direction side and the opposite side. Since α is provided, the distance L1 on the welding progress direction side is longer than the distance L2 on the opposite side. When the MIG arc 15 and the plasma arc 14 are generated in this state, the distance L2 between the tip of the plasma electrode 8 opposite to the welding progress direction and the work piece is shorter than the distance L1, and therefore the voltage gradient is high. Therefore, the plasma arc 14 is easily generated. As a result, as shown in FIG. 10, plasma arcs 14 having different plasma densities are generated on the welding progress direction side and the opposite side.

  As a result, when the work piece is an aluminum alloy, when the advance angle α is provided, the plasma arc 14 is concentrated on the opposite side of the welding progress direction, so that the cleaning action does not work and the oxide film cannot be destroyed. . Moreover, since the energy of the plasma arc 14 is concentrated on one side of the weld bead, the molten metal is overheated, the bead appearance becomes white, and the appearance is impaired. Further, when the workpiece 16 is an iron-based material such as mild steel or stainless steel, a convex bead or a humping bead is formed, and the weld bead surface is not smooth.

  An object of the present invention is to provide a plasma electrode and a plasma MIG welding torch capable of obtaining a beautiful welding bead.

The first invention is
A power supply tip for supplying power by inserting a welding wire into a wire insertion hole formed in the shaft core;
A plasma electrode provided coaxially with the feeding chip;
A plasma nozzle that surrounds the plasma electrode and is supplied with plasma gas;
In the plasma electrode of the plasma MIG welding torch that includes the shield nozzle that surrounds the plasma nozzle and is supplied with a shield gas,
The plasma electrode has a cylindrical shape having conductivity, is formed hollow so that the power feed tip can be inserted from a base end portion, a wire insertion hole is formed in a distal end surface, and is perpendicular to the distal end surface and the shaft core. The tip surface angle is formed with the direction surface,
The tip electrode angle is a plasma electrode characterized by being substantially equal to the advance angle of the plasma MIG welding torch.

The second invention is
A power supply tip for supplying power by inserting a welding wire into a wire insertion hole formed in the shaft core;
A plasma electrode provided coaxially with the feeding chip;
A plasma nozzle that surrounds the plasma electrode and is supplied with plasma gas;
In the plasma electrode of the plasma MIG welding torch that includes the shield nozzle that surrounds the plasma nozzle and is supplied with a shield gas,
The plasma electrode has a cylindrical shape having conductivity, is formed hollow so that the power feed tip can be inserted from a base end portion, a wire insertion hole is formed in a distal end surface, and is perpendicular to the distal end surface and the shaft core. The tip surface angle is formed with the direction surface,
This tip surface angle is approximately equal to (180 degrees-receding angle of the plasma MIG welding torch).

The third invention is
A plasma MIG welding torch comprising the plasma electrode according to the first invention or the second invention.

  The plasma electrode and the plasma MIG welding torch of the present invention can obtain a beautiful weld bead because the plasma arc does not concentrate on the opposite side of the welding progress direction.

[Embodiment 1]
DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described based on examples with reference to the drawings. FIG. 1 is a diagram showing a six-sided view of the plasma electrode of the present invention, wherein FIG. 1 (A) shows a front view, FIG. 1 (B) shows a rear view, and FIG. 1 (C) shows a left side view. (D) shows a right side view, (E) shows a plan view, and (F) shows a bottom view. In the figure, a plasma electrode 3 is a cylindrical column having conductivity and made of a copper alloy or the like, and is formed hollow so that a power feed tip is inserted from a base end portion (X2 direction in FIG. 1), and a distal end surface 3a. The wire insertion hole is formed in. Further, as compared with the conventional plasma electrode shown in FIG. 5, an angle θ <b> 2 is formed by the tip surface 3 a of the plasma electrode and the surface 4 perpendicular to the axis 1. As will be described later, this angle θ2 is determined in advance corresponding to the advancing angle or the receding angle of the plasma MIG welding torch 6. Further, the threaded portion 26 of the conventional plasma electrode 8 is not formed on the side surface of the base end portion of the plasma electrode 3, and instead, two projecting portions 25, 25 are formed. 25 are inserted into the torch body 24 described later with reference to FIG. 2, the plasma electrode 3 is fixed by being caught by the torch body 24.

  The reason why the two projecting portions 25 and 25 are formed instead of the threaded portion on the side surface of the base end portion of the plasma electrode 3 is that the plasma electrode of the present invention is attached to the torch body described later of the plasma MIG welding torch. It is because it is necessary to attach in the direction decided with respect to the welding direction.

  FIG. 2 is a cross-sectional view of the plasma MIG welding torch according to the first embodiment of the present invention and a diagram showing an arc generation state, and shows a case where welding is performed at an advance angle. In the figure, the same functions as those of the plasma MIG welding torch 5 of the prior art shown in FIG. In the case of general joint welding, the plasma MIG welding torch 6 is welded by forming an advancing angle α in order to improve the shielding performance by leveling the welding bead. In general, the advancing angle α is 10 to 15 degrees. For example, when the advanced angle α is 10 degrees, the angle θ2 of the tip surface 3a of the plasma electrode is formed to be equal to the forward angle 10 degrees as shown in FIG. When formed in this way, the front end surface 3a of the plasma electrode and the surface of the workpiece 16 are parallel to each other, and the distance between the front end surface 3a of the plasma electrode and the workpiece 16 is the welding progress direction side L3 and the opposite side. It becomes the same distance with L4. As a result, a symmetric plasma arc 14 can be generated around the MIG arc 15, and the potential gradient between the plasma electrode 3 and the workpiece 16 is the same on the welding progress direction side and the opposite side. The plasma density will be the same.

  As a result, when the workpiece 16 is an aluminum alloy, the plasma arc 14 does not concentrate on the opposite side of the welding direction, so that the cleaning width of the plasma arc 14 can be ensured. In addition, since the energy of the plasma arc 14 is not concentrated on one of the weld beads and the phenomenon that the molten metal is partially overheated can be avoided, a beautiful weld bead can be obtained. Further, even when the workpiece 16 is an iron-based material such as mild steel or stainless steel, it is possible to obtain a weld bead having a smooth surface and without forming a convex bead or a humping bead.

  In the experiments by the inventors, when the work piece is aluminum and an aluminum alloy, the MIG arc current is 280 A, the MIG arc voltage is 28 V, the plasma arc current is 50 A, the plasma arc voltage is 400 V, the diameter of the welding wire is 1.2 mm, and the welding is performed. Plasma MIG welding was performed by setting the wire feed speed to 13 m / min, the advancing angle of the plasma MIG welding torch and the angle of the tip surface of the plasma electrode to 10 degrees. As a result, a beautiful weld bead could be obtained.

  Also, when the workpiece is an iron-based material, the MIG arc current is 60A, the MIG arc voltage is 22V, the plasma arc current is 100A, the plasma arc voltage is 35V, the diameter of the welding wire is 1.2mm, and the welding wire feeding speed The plasma MIG welding was carried out with the advancing angle of the plasma MIG welding torch and the angle of the tip surface of the plasma electrode being 10 degrees. As a result, a beautiful weld bead could be obtained.

  Further, the advancing angle α of the plasma MIG welding torch is set to 20 degrees, and as will be described later with reference to FIG. 5B, the angle θ2 of the front end surface 20a of the plasma electrode is set to 20 degrees. As a result of welding, a beautiful weld bead was obtained.

  According to further experiments by the inventors, as shown in FIG. 3, when the angle θ2 of the tip surface 3a of the plasma electrode is 10 degrees (the plasma electrode shown in FIG. 5A), the advance angle α is 5 It could be applied to plasma MIG welding in the range of up to 15 degrees. In addition, when the angle θ2 of the tip surface 20a of the plasma electrode is 20 degrees (the plasma electrode shown in FIG. 5B), it can be applied to plasma MIG welding in which the advance angle α is in the range of 15 degrees to 25 degrees. It was. FIG. 3 is a diagram showing the relationship with the advance angle α of the plasma MIG welding torch that can be applied when the tip surface angle of the plasma electrode of the present invention is 10 degrees and 20 degrees. As shown in the figure, one plasma electrode having a tip surface angle θ2 of 10 degrees can be applied to general plasma MIG welding with a forward angle of 10 to 15 degrees. Furthermore, by preparing two types of plasma electrodes having a tip surface angle θ2 of 10 degrees and 20 degrees, it can be applied to a wide range of plasma MIG welding with a forward angle of 5 to 25 degrees.

  Although FIG. 3 shows the case where two types of plasma electrodes having a tip surface angle of 10 degrees and 20 degrees are prepared, this is an example, and the tip surface angle may be determined more finely.

[Embodiment 2]
In the plasma MIG welding torch of the present invention, the case where the plasma MIG welding torch 6 has the advancing angle α has been described, but the present invention can be similarly applied to the case where the receding angle is provided. FIG. 4 is a cross-sectional view of the plasma MIG welding torch according to the second embodiment of the present invention and a diagram showing an arc generation state, and shows a case where welding is performed at a receding angle. In the figure, the same functions as those of the conventional plasma MIG welding torch 5 shown in FIG. Generally, the receding angle β of the plasma MIG welding torch is 10 to 15 degrees. For example, when the receding angle β is 10 degrees, as will be described later with reference to FIG. 5C, the angle θ2 of the tip surface 21a of the plasma electrode is formed so that (180 degrees−retracting angle 10 degrees) = 170 degrees. Yes. When formed in this manner, the tip surface 21a of the plasma electrode and the surface of the workpiece 16 are parallel to each other as in the first embodiment, and a symmetrical plasma arc 14 can be generated around the MIG arc 15. Since the potential gradient between the plasma electrode 3 and the workpiece 16 is the same on the welding direction side and the opposite side, the plasma density is also the same.

  As a result, when the workpiece 16 is an aluminum alloy, the cleaning width of the plasma arc 14 can be secured. In addition, since the energy of the plasma arc 14 is not concentrated on one of the weld beads and the phenomenon that the molten metal is partially overheated can be avoided, a beautiful weld bead can be obtained. Even when the workpiece 16 is an iron-based material such as mild steel or stainless steel, a weld bead having a smooth surface and a beautiful surface can be obtained.

  Further, the receding angle β of the plasma MIG welding torch is set to 20 degrees, and the angle θ2 of the tip surface 22a of the plasma electrode is set to (180 degrees−retreating angle 20 degrees) = 160 degrees as described later with reference to FIG. As a result of performing plasma MIG welding in the same manner as described above, a beautiful weld bead could be obtained. FIG. 5 is a view showing the plasma electrode of the present invention, and FIG. 5A shows that the tip surface angle θ2 is formed at 10 degrees corresponding to the case where the advance angle α is 10 degrees. FIG. 5B shows the case where the front end face angle θ2 is formed at 20 degrees corresponding to the case where the advance angle α is 20 degrees. FIG. 5C shows the case where the tip end face angle θ2 is formed at 170 degrees corresponding to the case where the receding angle β is 10 degrees. FIG. 4D shows that the tip surface angle θ2 is formed at 160 degrees corresponding to the case where the receding angle β is 20 degrees.

  According to further experiments by the inventors, as shown in FIG. 6, when the angle θ2 of the plasma electrode tip surface is 170 degrees (the plasma electrode shown in FIG. 5C), the receding angle β is 5 degrees. It could be applied to plasma MIG welding up to -15 degrees. In addition, when the angle θ2 of the tip surface of the plasma electrode is 160 degrees (plasma electrode shown in FIG. 5D), the receding angle β can be applied to plasma MIG welding in the range of 15 degrees to 25 degrees. . FIG. 6 is a diagram showing the relationship with the receding angle β of the plasma MIG welding torch which can be applied when the tip surface angle of the plasma electrode of the present invention is 170 degrees and 160 degrees. As shown in the figure, one plasma electrode having a tip surface angle θ2 of 170 degrees can be applied to general plasma MIG welding with a receding angle of 10 to 15 degrees. Furthermore, by preparing two types of plasma electrodes having a tip surface angle θ2 of 170 degrees and 160 degrees, it can be applied to a wide range of plasma MIG welding with a receding angle of 5 to 25 degrees.

  Although FIG. 6 shows a case where two types of plasma electrodes having a tip surface angle of 170 degrees and 160 degrees are prepared, this is an example, and the tip surface angle may be determined more finely.

It is a figure which shows the 6th surface figure of the plasma electrode of this invention. It is sectional drawing of the plasma MIG welding torch of Embodiment 1 of this invention, and a figure which shows the generation | occurrence | production state of an arc. It is a figure which shows the relationship with the advance angle (alpha) of the plasma MIG welding torch applicable when the front end surface angle of the plasma electrode of this invention is 10 degree | times and 20 degree | times. It is sectional drawing of the plasma MIG welding torch of Embodiment 2 of this invention, and a figure which shows the generation | occurrence | production state of an arc. It is a figure which shows the plasma electrode of this invention. It is a figure which shows the relationship with receding angle (beta) of the plasma MIG welding torch applicable when the front end surface angle of the plasma electrode of this invention is 170 degree | times and 160 degree | times. It is a block diagram of the plasma MIG welding torch 5 of a prior art. It is a figure which shows the plasma electrode of a prior art. It is a figure which shows the state which provides advancing angle and welds using the plasma MIG welding torch 5 of a prior art. It is a figure which shows the state which generated the arc using the plasma MIG welding torch 5 of a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Axis core 2 Plasma electrode 2a Plasma electrode tip surface 3 Plasma electrode 3a Plasma electrode tip surface 4 Surface perpendicular to axis 1 5 Plasma MIG welding torch 6 Plasma MIG welding torch 7 Feed tip 8 Plasma electrode 8a Plasma electrode tip surface 9 Plasma nozzle 10 Shield nozzle 11 Center gas 12 Plasma gas 13 Shield gas 14 Plasma arc 15 MIG arc 16 Workpiece 17 Welding wire 18 Feed roll 20 Plasma electrode 20a Plasma electrode tip surface 21 Plasma electrode 21a Plasma electrode tip surface 22 Plasma electrode 22a Plasma electrode tip 23 Torch body 24 Torch body 25 Protrusion 26 Screw part 27 Plasma MIG welding torch Fc Wire feed control signal Fw Welding wire 17 feed speed Iwm Mig arc current Iwp Plasma arc power Flow L1 Welding direction distance L2 Welding direction distance L3 Welding direction direction distance L4 Welding direction direction distance PSM Mig welding power source PSP Plasma welding power source Vwm Mig arc voltage Vwp Plasma arc voltage WM Wire Feed motor α Advance angle θ1 of plasma MIG welding torch Angle θ2 formed by tip surface 8a of plasma electrode and shaft core 1 Angle formed by tip surface of plasma electrode and surface 4 perpendicular to shaft core 1

Claims (3)

A power supply tip for supplying power by inserting a welding wire into a wire insertion hole formed in the shaft core;
A plasma electrode provided coaxially with the feeding chip;
A plasma nozzle that surrounds the plasma electrode and is supplied with plasma gas;
In the plasma electrode of the plasma MIG welding torch that includes the shield nozzle that surrounds the plasma nozzle and is supplied with a shield gas,
The plasma electrode has a cylindrical shape having conductivity, is formed hollow so that the power feed tip can be inserted from a base end portion, a wire insertion hole is formed in a distal end surface, and is perpendicular to the distal end surface and the shaft core. The tip surface angle is formed with the direction surface,
The plasma electrode according to claim 1, wherein the tip surface angle is substantially equal to the advance angle of the plasma MIG welding torch.
A power supply tip for supplying power by inserting a welding wire into a wire insertion hole formed in the shaft core;
A plasma electrode provided coaxially with the feeding chip;
A plasma nozzle that surrounds the plasma electrode and is supplied with plasma gas;
In the plasma electrode of the plasma MIG welding torch that includes the shield nozzle that surrounds the plasma nozzle and is supplied with a shield gas,
The plasma electrode has a cylindrical shape having conductivity, is formed hollow so that the power feed tip can be inserted from a base end portion, a wire insertion hole is formed in a distal end surface, and is perpendicular to the distal end surface and the shaft core. The tip surface angle is formed with the direction surface,
The plasma electrode characterized in that the tip surface angle is substantially equal to (180 degrees-receding angle of the plasma MIG welding torch).
  A plasma MIG welding torch comprising the plasma electrode according to claim 1.

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