JP2000246436A - Device for cladding by welding using tig arc - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform cladding by welding so that a base material side is not melted though a TIG arc having a high current is used for performing overlay welding with high efficiency. SOLUTION: This is a device for cladding by welding, which performs the cladding by welding of an adding wire 10 sent from a wire torch to a base material 13 by using a TIG torch 2 and the wire torch 3. A TIG arc having an arc current of 300 A or over is generated by the TIG torch. For the tungsten electrode 4 of the TIG torch, the tip of the electrode is oscillated and moved with amplitude of 10 mm or over and a frequency of 10 Hz or over, and the TIG arc performing the cladding by welding is used by adding the above adding wire 10 having a melting point lower than that of the base material. An arc current is caused to flow to the extent that the surface of the base material is hardly melted or the moving speed of the tungsten electrode must be set to the same extent. By controlling the quantity of the arc current synchronously with the oscillating phase of the electrode to the surface of the base material, the surface of the base material is almost uniformly heated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a TIG arc welding apparatus, and more particularly to an apparatus suitable for broadly depositing a different material on a base material.

[0002]

2. Description of the Related Art In the case of overlay welding using a TIG arc, conventionally, a TIG arc torch and a wire-added torch are integrally combined, or a TIG arc torch with a fixed wire torch is weaved at a frequency of 10 Hz or less. Moving). In the case where the movement width of the arc is relatively narrow, such as less than 10 mm, a device that swings a tungsten electrode at about 10 Hz as described in Japanese Patent Application Laid-Open No. 7-276050 according to the same applicant as the present application is known. Alternatively, a device for oscillating a tungsten electrode at a frequency such as 50 Hz and at a high speed has been proposed prior to the filing of the present application, but they are not intended to oscillate the arc by 10 mm or more in the first place due to the configuration of the device. Was.

In any case, when the arc is to be moved in a width exceeding 10 mm, conventionally, the entire TIG torch is usually mounted on a slide base or a robot and the arm of the robot is used to move the TIG torch. In most cases, 1
The weaving frequency was lower than 0 Hz. For example, the cladding apparatus disclosed in Japanese Patent Application Laid-Open No. 52-113346 reciprocates 100 times per minute, and the cladding apparatus disclosed in Japanese Patent Application Laid-Open No. 62-212065 reciprocates 120 to 270 times per minute. The material is being melted.

On the other hand, as an example of using a TIG arc without melting a base material, a copper-silicon alloy is used as a brazing material, for example, in order to externally smooth a joint of a sheet metal portion of an automobile. It has been known that TIG brazing in which a base material and a brazing material are heated and filled with TIG is performed. In this case, since the TIG arc occurs on the thin plate,
A low arc current, such as 0A to 70A, is employed and the torch moves along the seam without rocking.

[0005]

In a conventional apparatus using a TIG arc, the TIG arc basically melts the base material to form a sufficient penetration. In many cases, dilution with a base material was often a problem. In particular, when overlaying copper or copper alloy on carbon steel, molten copper and molten iron component hardly form a solid solution, so the deposited metal has a mixed structure of copper and iron. Free iron was formed and often appeared on the surface of the build-up metal, deteriorating wear resistance and corrosion resistance.

Another problem remains that copper enters the austenite crystal grain boundaries in the part coarsened by the influence of welding heat on the carbon steel side (copper immersion phenomenon), thereby lowering the ductility of the carbon steel.

In addition, when overlaying a copper alloy on carbon steel, the first layer can be relatively easily welded because the base material is a material having low thermal conductivity. The welding work becomes difficult because the metal is built up on the metal component having a high thermal conductivity as it becomes visible. Therefore, when the required build-up thickness exceeds 3 mm, it usually becomes a multi-layer build-up, but if the build-up thickness is up to about 6 mm, it is desirable to complete the build-up as much as possible.

However, if the bead width is narrow, the wetting angle of the bead toe becomes large, and a defective fusion portion is formed by overlapping the beads when placing adjacent beads. There was a problem that welding conditions could not be adopted.

When a copper alloy containing zinc is built up, zinc is easily evaporated because of its low vapor pressure.
Hardfacing using an arc is difficult to work because it generates a large amount of fumes of zinc or zinc oxide, and pores generated by the boiling of zinc in the cladding metal remain. It was usual to build up with a gas flame that did not get too hot. However, overlaying using a gas flame has a problem that the working time is extremely long.

A first object of the present invention is to provide a high-efficiency cladding for a metal whose melting point is lower than the melting point of the base metal, such as when a copper alloy is clad on carbon steel. For this reason, a device for overlay welding while trying not to melt the base material side while using a large current TIG arc, and also trying to minimize the crystal grains on the base material side of the build-up boundary portion of the base material as much as possible. To provide.

Another object of the present invention is to form a thicker build-up by forming a wide build-up bead using a TIG arc.

A second object of the present invention is to provide an apparatus for reducing the generation of fumes such as zinc fumes by minimizing the occurrence of arcs directly from the additive wire or the molten metal forming the molten pool. .

[0013]

In order to solve the above problems, the present invention mainly employs the following configuration.

An overlay welding apparatus for overlay welding an additional wire from the wire torch to a base material using a TIG torch and a wire torch, wherein the TIG torch generates a TIG arc having an arc current of 300 A or more. The tungsten electrode of the torch is oscillated at the tip of the electrode at an amplitude of 10 mm or more and at a frequency of 10 Hz or more, and the addition wire having a melting point lower than that of the base material is added and the overlay welding using a TIG arc is performed. Welding equipment.

[0015] In the overlay welding apparatus using the TIG arc, an arc current is applied to the base material so as to hardly melt the surface of the base material or the TIG arc is used as a moving speed of the tungsten electrode. Welding equipment.

In the overlay welding apparatus using the TIG arc, the magnitude of the arc current is controlled in synchronization with a swing phase of the electrode with respect to the surface of the base material so that the surface of the base material is substantially uniform. Welding equipment using a TIG arc that heats to a high temperature.

Further, in the overlay welding apparatus using the TIG arc, the magnitude of the arc current is kept constant,
An overlay welding apparatus using a TIG arc that controls an electrode swing speed in accordance with the electrode swing phase to heat the base material surface substantially uniformly.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A TIG arc welding apparatus according to an embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is an explanatory view schematically showing a welding head 1 during overlay welding using the overlay welding apparatus of the present embodiment. FIG.
Is T when the welding head 1 of FIG. 1 is viewed from the welding direction.
It is explanatory drawing which showed roughly the connection state of IG arc torch 2, wire torch 3, and welding power supply.

Here, 1 is a welding head, 2 is a TI
G torch, 3 for wire torch, 4 for tungsten electrode,
5 is an electrode actuator, 6 is an insulating material, 7 is a copper chip,
8 is a support, 9 is a housing, 10 is a wire, 11 is a contact tube, 12 is a ceramic guide, 13 is a base material, 1
4 is a molten pool, 15 is a wire power supply, 16 is an arc power supply, 1
7 is an arc, 18 is a shaft axis, 19 is a shield nozzle, 2
0 represents an overlay bead.

Inside the welding head 1 shown in FIG.
A mechanism for swinging the G torch 2 like a pendulum is incorporated. That is, a toe having a tungsten electrode 4 attached to the tip end.
The TIG torch 1 is mechanically directly connected to the electromagnetic actuator 5 via an insulating member 6, and the TIG torch 1 is restrained from both sides by springs (not shown). By the action of the driving force and the spring, 10
Since it is configured to oscillate by self-excited oscillation at a frequency of not less than Hz, it always oscillates at resonance or near resonance.

In the TIG welding apparatus proposed previously, the swing amplitude of the tungsten electrode is 5 mm or less, and the spring constant is 30 N / mm in order to swing at a frequency as high as possible.
In the embodiment of the present invention, in order to increase the swing amplitude, the spring constant is set to 20 N / mm.
The following small weak springs were used. Here, the TIG torch 2 is connected to two cooling water hoses (not shown), and the copper tip 7 holding the tungsten electrode at the tip of the torch is water-cooled.

The electromagnetic actuator 5 is fixed to a housing 9 of the welding head 1 by a support 8. On the other hand, the addition wire 10 is supplied from a wire feeder (not shown) to the contact tube 1 via a conduit (not shown).
1. It is fed to the molten pool 14 on the base material 13 through the ceramic guide 12.

As shown in FIG. 2, the wire torch 3
a, 3b, and 3c, each of which is separately connected to the + terminal side of three wire heating power supplies 15a, 15b, and 15c. And each wire power supply 15a, 15b, 15c
Is connected to the base material 13. Also TIG
The torch 2 is connected to the negative terminal side of the arc power supply 16, and the positive terminal of the arc power supply 16 is connected to the base material 13. In this manner, the arc 1 is placed between the tungsten electrode 4 and the base material 13.
7 is formed.

The tip of the tungsten electrode 4 swings sinusoidally in a pendulum shape as shown by an arrow in FIG. 2 with the axis 18 of the electromagnetic actuator 5 as a fulcrum. The distance from the shaft 18 to the tip of the tungsten electrode 4 is about 200 mm. When the TIG torch 2 swings ± 7.1 degrees, the total swing width of the tip is 50 m.
m. A gas hose (not shown) is connected to the housing 9 so that the shield gas flows out of a shield nozzle 19 attached to surround the TIG torch 2 and the wire torch 3. In this way, the wire 10 is supplied to the arc 17 generating portion, and the base material 1
A build-up bead 20 is formed on 3.

In Table 1, using the apparatus of FIGS. 1 and 2,
Pure copper and copper (20% Zn-80% Cu) on mild steel plate
Shows the proper welding conditions when overlay welding was performed.

[0026]

[Table 1]

Since the wire is heated and added to near the melting point by the hot wire method, the amount of heat used to melt the wire by the arc is relatively small, and most of the arc heat is used for heating the base material. Therefore, it is better to heat the base metal with a large heat input as much as possible in order to achieve high-efficiency overlay welding, and it is better to increase the arc current as much as possible.

However, a high current T exceeding 300 A
The IG arc increases the concentration of the arc and strongly melts the base metal, so that the base metal component dissolves in the overlay metal. However, when the tungsten electrode is moved over the base material at a high speed, the arc cannot locally melt the base material. It has been found that such a state can be achieved when the rocking width is 10 mm or more and the rocking frequency is 10 Hz or more.

When the arc current is set to 300 A or less, the base material heating ability is weakened, and the work cannot be performed very efficiently.

The overlay thickness can be adjusted mainly by controlling the wire feeding speed. The welding speed is selected to be an appropriate speed for heating the base material according to the base material and the build-up width.

The wire may be inserted from the front side or the rear side in the welding progress direction. However, when overlaying a wire containing a large amount of zinc, such as brass or brass, it is preferable to insert the wire from the rear side. As shown in FIG. 2, the wire 10 is connected so as to be positive. That is, the arc 17 is blown away from the wire by magnetic blowing by the wire current, and since the wire 10 is inserted into the molten pool behind the arc 17, the arc 17 is blown forward of the molten pool 14 and It is generated directly from the material 13. This reduces the zinc loss due to evaporation.

According to the embodiment of the present invention, the positive terminal of the wire heating power supply is connected to the power supply terminal to the wire side, the base material side is connected to the negative side of the wire heating power supply, and a direct current is supplied to the additional wire to heat the wire. The TIG arc formed by connecting the tungsten electrode to the minus (-) side of the arc power source by adopting the hot wire method of They try not to approach.

In the welding head 1 of the present embodiment, the tip of the tungsten electrode 4 moves in a sine wave shape as shown in FIG. The time that the arc stays is relatively longer than the time that it stays near the center of the swing.

In other words, for example, the TIG torch 2
In FIG. 2, starting from the center position, moving rightward, turning back at the right end (time point π / 2), moving leftward, reaching the left end (time point 3π / 2), and changing the direction to return to the original position. Looking at the process of returning to the center position (time point 2π), the time at which the arc is exposed to the base material is longer at the right end and the left end or in the vicinity thereof than at the center position. Exposed, but the time interval is lengthened, and the portion of the base metal exposed to the arc during that time interval will shift).

For this reason, when the arc current is fixed at 450 A as shown by the broken line in FIG. 3, the penetration of the base material at both ends of the bead 21 becomes deep as seen in the cross-section of the overlay bead in FIG. However, it is desirable that the base material be uniformly mixed in the overlay. In particular, when a copper alloy is clad on carbon steel, it is preferable that the cladding be able to be clad without melting into the base material.

Therefore, as shown by the solid line in FIG. 3, the arc current is reduced to 350 A in synchronization with the oscillation phase, that is, near the maximum amplitude position, and is reduced by 50 A near the oscillation center.
When the temperature was increased to 0A, a bead 22 which did not melt into the base material and had the cladding boundary properly fused with the base material 13 could be formed as shown in FIG.

In FIG. 3, the arc current is controlled in accordance with the sinusoidal movement of the tungsten electrode. However, the movement of the TIG torch is controlled so that the arc current is constant and the surface heating state of the base material is constant. By doing so, good base material heating can be achieved. In this case, it is necessary to use a servomotor as the electromagnetic actuator to control the moving speed of the tungsten electrode at the oscillating end portion to be high and the moving speed at the oscillating center portion to be low.

In this embodiment, in order to form a wide bead, a swing width of 50 mm and three wire torches are used. However, if the flowability of the metal to be built up is good, one wire may be used. To increase the number, the number of wire torches may be further increased.

Further, the additive wire may be a wire material containing a metal having a low evaporation temperature such as Zn (see Table 1), and the additive wire may be heated by energizing to increase the melting rate of the wire.

As described above, the embodiments of the present invention include those having the following configuration examples and functions or functions. In order to generate a TIG arc while oscillating the tungsten electrode tip with an amplitude of 10 mm or more and a frequency of 10 Hz or more, add a wire while generating a TIG arc of an arc current of 300 A or more, and weld overlaid broadly. Constitute. An arc current and a moving speed are set so as not to melt the surface of the base material, and the welding is performed more favorably by overlaying while adding a wire having a lower melting point than the base material.

In these cases, the arc current is controlled in synchronism with the electrode oscillating phase, or the electrode oscillates while keeping the arc current constant, so as to heat the base material surface under the oscillating arc as uniformly as possible. It is preferable to control the electrode swing speed in accordance with the phase.

Further, it is preferable to increase the wire melting rate by heating the wire to a temperature near the melting point by electrically heating the added wire.

[0043]

According to the present invention, a TIG arc capable of widely and efficiently heating a base material can be used as a heat source, and the wire is electrically heated to melt the wire more effectively. Has become remarkably efficient and economical. In particular, a brass alloy containing a large amount of zinc had to be gas-welded in the past, but according to the present invention, the TIG arc can be built up, so that the working efficiency can be remarkably improved.

Further, according to the present invention, for example, copper or a copper alloy can be overlay-welded without almost melting the base material carbon steel. In other words, the dilution of the build-up metal by the base material is very small, which is a degree of dissolution due to the metallurgical reaction of the molten build-up metal with the base material. In addition, when overlaying copper or a copper alloy on carbon steel, according to the present invention, coarsening hardly progresses under the influence of welding heat on the carbon steel side,
Further, copper does not substantially enter the austenite crystal grain boundary, and even if it does, the copper penetration depth is extremely shallow, and the ductility of the base carbon steel is not reduced to a practically problematic level.

Since a bead width of 55 mm and a thickness of 6 mm can be built up in one layer, a build-up portion that is not too wide and not too thick, such as a bearing portion, is formed in one pass, that is, an adjacent bead in which defects easily enter. Can be completed without overlapping.

As described above, the present invention has a great industrial effect when applied to overlay welding having a melting point lower than that of the base metal, such as when overlaying a copper alloy on carbon steel.

[Brief description of the drawings]

FIG. 1 is a view showing a build-up welding apparatus using a TIG arc according to an embodiment of the present invention.

FIG. 2 is a view of the overlay welding apparatus of FIG. 1 as viewed from a welding progress direction.

FIG. 3 is a diagram illustrating arc current control according to the present embodiment.

FIG. 4 is an example of a cross-sectional view of a poor build-up bead.

FIG. 5 is an example of a cross-sectional view of a proper build-up bead.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Welding head 2 TIG torch 3 Wire torch 4 Tungsten electrode 5 Electrode actuator 6 Insulation material 7 Copper chip 8 Support stand 9 Housing 10 Wire 11 Contact tube 12 Ceramic guide 13 Base material 14 Melt pool 15 Wire power supply 16 Arc power supply 17 Arc 18 axis Core shaft 19 Shield nozzle 20 Overlay bead

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Toshiharu Nagashima 5-3 Takaracho, Kure-shi, Hiroshima Fab term in Bab Hitachi Industrial Co., Ltd. (reference) 4E001 AA03 BB07 CA01 DA07 DC01 DC02 DF04 EA01

Claims (7)

[Claims] 1. An overlay welding apparatus for overlay welding an additional wire from the wire torch to a base material using a TIG torch and a wire torch, wherein the TIG torch generates a TIG arc having an arc current of 300 A or more, The tungsten electrode of the TIG torch has an amplitude of 10 mm
A build-up welding apparatus using a TIG arc, characterized in that the tip of the electrode is swung at a frequency of 10 Hz or higher, and the addition wire is added and the build-up welding is performed. 2. The overlay welding apparatus using a TIG arc according to claim 1, wherein the moving speed of the tungsten electrode when an arc current is applied or swings so that the surface of the base material is hardly melted. A build-up welding apparatus using a TIG arc. 3. The overlay welding apparatus using a TIG arc according to claim 1 or 2, wherein the magnitude of the arc current is controlled in synchronization with a swing phase of the electrode with respect to the surface of the base material, A build-up welding apparatus using a TIG arc, wherein the base material surface is heated substantially uniformly. 4. The overlay welding apparatus using a TIG arc according to claim 1, wherein the magnitude of the arc current is kept constant, and the electrode swing speed is adjusted in accordance with the swing phase of the electrode. A build-up welding apparatus using a TIG arc, wherein the surface of the base material is controlled to be heated substantially uniformly. 5. The overlay welding apparatus using a TIG arc according to claim 1, wherein the additional wire is heated by energizing to increase a melting rate of the additional wire. Overlay welding equipment using TIG arc. 6. The overlay welding apparatus using a TIG arc according to claim 5, wherein, when the additional wire is electrically heated, the additional wire is connected to a + side of a DC power supply and the base material is connected to a − side. And the TIG arc is prevented from approaching the additive wire. 7. The overlay welding apparatus using a TIG arc according to claim 3, 4 or 5, wherein the additive wire is made of a material containing a metal having a low evaporation temperature. Overlay welding equipment.