JP2685989B2 - Plasma overlay equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma overlaying apparatus for supplying a metal powder into an arc where a plasma torch is generated and performing overlay welding on a base material facing the torch. .

[0002]

2. Description of the Related Art In order to reinforce and improve a metal surface (improve wear resistance, heat resistance, corrosion resistance, etc.), overlay welding has been conventionally performed. A conventional plasma overlaying apparatus includes a plasma torch, a plasma power source for forming an arc between a main electrode of the torch and a base material, and powder for supplying metal powder into the formed arc. A supply means and a drive means for moving at least one of the torch and the base material relative to the other. In the overlay welding process, powder metal is supplied into the plasma arc column, melted by an arc, and collides with the plasma arc along the welding surface of the base metal. A plasma torch or base metal is driven during this build-up welding, whereby a build-up layer of the required thickness is formed on the base material. A plasma torch used for this purpose is disclosed in, for example, Japanese Patent Laid-Open No. 1-218772. The tip portion of this type of plasma torch has a structure as shown in FIG. 9 or 10, for example. In each figure, 51 is a tungsten electrode, 52 is a plasma gas, 53 is a powder, 54 is a powder carrier gas,
55 is cooling water, 56 is a shield gas, 57 is a plasma arc column, 58 is a molten metal, 59 is a base material, and 60 is a nozzle member (insert tip). In the torch shown in FIG. 9, the nozzle member 60 is provided with a plasma injection hole and a plurality of powder supply holes 60a formed around the plasma injection hole,
The powder 53 is supplied into the plasma arc column 57 from the powder supply hole 60a through the powder carrier gas supply passage 31 together with the carrier gas 54. Powder carrier gas supply path 31
There is a ring-shaped space that surrounds the arc hole between the lower opening and the upper opening of the powder supply hole 60a. In the torch shown in FIG. 10, two nozzles 61 and 62 are concentrically provided, and a plasma arc is squeezed and ejected by an inner nozzle 61, and a carrier gas 54 is discharged from a gap between the two nozzles.
At the same time, the powder 53 is supplied into the plasma arc column 57.

FIG. 11 shows a state of overlaying using a conventional plasma overlaying device. As shown in FIG. 11, metal powder 53 for overlaying is supplied into the arc 57, and the plasma torch is further moved at a predetermined speed in the direction of A in the figure to overlay. In the figure, 56 is a shield gas, 58 is a deposited metal, 58a is a built-up metal, 58b is a base metal penetration portion, 59 is a base material, and 60 is a nozzle member.

[0004]

By the way, in the conventional plasma powder overlay welding, the width of the overlayed metal 58a (the cross-sectional width in the direction orthogonal to the moving direction of the torch) is relatively wide. , The height is low. This may not be suitable when a small and high buildup is required, especially when the base material to be processed is relatively small and a narrow buildup is required. The build-up width can be narrowed to some extent by reducing the size of the plasma torch, but if the arc becomes smaller, the required penetration cannot be obtained, so there is a limit to downsizing the torch.

It is an object of the present invention to provide a plasma overlaying apparatus capable of obtaining a overlay with a relatively small width and a relatively high height and good penetration quality.

[0006]

SUMMARY OF THE INVENTION The present invention provides a plasma transistor.
Plasma power source (20) for forming an arc between the main electrode (51) of the torch (1) and the torch (1) and the base material (59), and metal powder (53) in the formed arc. ), A powder supply means (30), and a drive means for moving at least one of the torch (1) and the base material (59) relative to the other. , A magnetic flux having a component orthogonal to the direction along the central axis of the main electrode (51) and the direction of movement in the space between the tip of the main electrode (51) of the torch (1) and the base material (59). It is characterized by including a magnetic flux generating means (2, 3, 10) for generating.

[0007]

According to this, the magnetic flux generating means (2, 3, 10) is
In the space between the tip of the main electrode (51) of the chi (1) and the base material (59), a magnetic flux having a component orthogonal to the direction along the central axis of the main electrode (51) and the direction of the movement is generated. Therefore, a deflection force acts on the arc generated in the space in the relative movement direction between the torch (1) and the base material (59) according to Fleming's left-hand rule. This causes the arc to swing in the moving direction. The metal powder (53) supplied to the arc moves with the arc, but due to the above deflection, the cross section of the arc (cross section parallel to the surface of the base metal) is roughly asymmetrical elliptical. It becomes (substantially egg-shaped), the melting width of the base material (direction orthogonal to the moving direction) becomes narrower, and the melting length (direction along the moving direction) becomes wider. The build-up width becomes narrower as the melting width becomes narrower, and the floating escape of gas components in the molten metal is promoted as the melting length spreads, and a high-quality build-up with no defects is obtained. .

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

[0009]

1 is a block diagram showing a schematic configuration of an embodiment of the present invention. A plasma power source 20 and a powder supply device 30 are connected to a plasma torch 1 having a powder supply path inside. A control device, a cooling water device, a shield gas source, a plasma gas source, a carrier gas source, and the like are connected to the plasma power source 20 and the powder supply device 30. Although not shown, there is also a drive device that drives one of the base material 59 and the torch 1 at a constant speed in a direction perpendicular to the paper surface, which is also connected to the control device. The configuration and connection of these are similar to those of the conventional plasma overlaying apparatus.

A magnetic pole piece 2 around which an exciting coil 3 is wound is attached to a plasma torch 1 of the plasma overlaying apparatus shown in FIG. 1, and the exciting coil 3 is connected to an oscillating control board 10. The oscillating control board 10 has a power supply circuit for energizing the exciting coil 3, and a value of energizing current, an on (energizing) / off (non-energizing) period and an energizing duty of the exciting coil 3 corresponding to the input operation of the operator. Set the tee and start
A control circuit is provided for starting energization of the exciting coil 3 in response to a power input, and stopping energization in response to a stop input. When the exciting coil 3 is energized, the magnetic pole piece 2 moves
A magnetic flux is generated that laterally crosses the space between the lower end of the chi and the upper surface of the base material 59. When there is a plasma arc from the torch 1 toward the base material 59, the arc is deflected to the back side of the paper surface or the front side.

FIG. 2 shows the positional relationship between the plasma torch 1 and the pole pieces 2 shown in FIG. 2A shows the lower surface of the plasma torch 1, and FIG. 2B shows the front surface (the same surface as FIG. 1). The front end surface of one end of the pole piece 2 is further below the torch 1 and faces the arc so that the magnetic flux generated from the front end surface crosses the arc column generated from the torch 1. FIG. 3 shows the right side surface of the plasma torch 1 shown in FIG. That is, FIG. 3 is a view of the tip of the plasma torch 1 viewed from the direction of arrow B in FIG. Torch 1
While supplying the powder 53 into the arc column 57 generated between the electrode rod 51 and the base material 59 therein, the base material 59
With respect to the direction of arrow A. Powder 53 supplied
Melts mainly in the arc and collides with the surface of the base material 59 to form a molten metal 58. The molten metal 58 is the base material 5
A welded portion 58b is formed on the surface of 9 and is fixed on the base material 59 as a build-up metal 58a as the torch 1 moves. In addition, 56 is a shield gas and 60 is a nozzle member (insert tip).

By the way, as described above, the pole piece 2 is
When a magnetic flux is generated across the space between the lower end of the die 1 and the upper surface of the base material 59, left and right in FIG. 1, and perpendicularly to the paper surface in FIG. 3, the magnetic flux causes the arc 57 to move like an arc 57a. B is bent in the moving direction A (FIG. 3). This bending of the arc corresponds to the strength of the magnetic flux generated from the magnetic pole piece 2 (current value of the exciting coil 3), and therefore, when the exciting coil 3 is intermittently energized in the oscillating control device 10 at regular intervals, or positive at regular intervals. When reverse alternating current is applied (current polarity is switched), the arc 57 swings (oscillates) in the moving direction A of the torch 1 at a constant cycle. The amplitude of the oscillator corresponds to the current value (arc current value and exciting coil current value), and the larger it is, the larger.

When the exciting coil 3 is not energized,
As shown in FIG. 5A, the arc 57 goes straight to the base material 59. When the exciting coil 3 is energized in the forward direction, the arc bends in the left direction A, as indicated by 57, as shown in FIG. When the exciting coil 3 is energized in the reverse direction, it turns to the right. As shown in FIGS. 5A and 5C, when the distance between the tip of the torch 1 and the base material 59 is 8 mm, the cross-sectional shape of the arc at the intermediate portion (A1-A2 line) is:
When the exciting coil 3 is not energized (a in FIG. 5), it has a circular shape as shown in FIG. 5 (c), but when the arc is bent by energizing the exciting coil 3, (d) in FIG. ), The width becomes an asymmetric elliptical shape and the width (minor axis diameter) in the direction orthogonal to the bending direction A becomes narrower than that when no current is applied. At this time, the bending amount of the arc is
Is 5 mm on the surface of. When the exciting coil 3 is energized for 0.5 second cycle with intermittent energization of 50% energizing duty (oscillating energization), the cross-sectional shape of the arc is every 0.25 seconds. To a large diameter circle (two-dot chain line of d in FIG. 5) and a narrow asymmetric ellipse shape (solid line of d in FIG. 5). The cross sectional shape is long in the A direction.

With the base material 59 and the torch 1 both stationary and fixed, overlay welding was performed for a predetermined time. The overlay welding conditions are plasma current 120 A, powder gas (argon) flow rate 2 liters / min, shield gas (argon) flow rate 5 liters / min, powder feed amount 5 g / mi.
n. FIG. 6 shows the outer shape of the obtained overlay metal. 6 (a) and 6 (b) are obtained from the direction orthogonal to the external shape and the direction A (perpendicular to the plane of FIG. 5) obtained from the direction A shown in FIGS. The external appearance is shown. When the exciting coil 3 is not energized, the overlay metal has a gentle rounded hill shape. 6C and 6D are orthogonal to the outer shape and the direction A seen from the direction A shown in FIGS. 3 and 5 obtained when the exciting coil 3 is energized with the above-described oscillator ( The external shape seen from the direction (perpendicular to the paper surface) is shown. When the exciting coil 3 is energized with an oscillating current, it becomes a steep mountain shape in a direction orthogonal to the bending direction (A) of the arc and extends long in the bending direction of the arc.
The width is narrower and the height is higher in the direction orthogonal to the direction A than when the oscillator is not energized.

Next, the plasma torch 1 is set to 120 mm / min.
The overlay welding was performed under the same conditions as the above overlay welding conditions while moving at the speed of. FIG. 7 shows the outer shape of the obtained overlay metal. 7A and 7B are obtained from the direction orthogonal to the outer shape and the direction A (shown in the direction A shown in FIGS. 3 and 5) obtained without energizing the exciting coil 3 and the direction perpendicular to the paper surface. The external appearance is shown. When the exciting coil 3 is not energized,
The steepness (height / width) of the overlay metal is small (1.5 /
7.1 = 0.211). 7 (c) and 7 (d) are shown in FIGS. 3 and 5 obtained when the exciting coil 3 is energized with the above-mentioned oscillation and the plasma torch 1 is moved in the direction A. FIG. The external shape seen from the direction A shown and the external shape seen from the direction orthogonal to the direction A (perpendicular to the paper surface) are shown. In this way, when the exciting coil 3 is energized with an oscillator current and the plasma torch 1 is moved in the same direction as the bending direction A of the arc due to this energization, the steepness is 1.9 / 5.5. = 0.34
It becomes 5 and becomes large. In addition, since the arc bends forward in the advancing direction, the melting length expands in the advancing direction, and in response to this, levitation and escape of gas components in the molten metal are promoted, and high-quality meat with no defects is obtained. The prime is obtained. In (e) and (f) of FIG. 7, the exciting coil 3 is energized with the above-described oscillation, and the plasma torch 1 is moved in the C direction opposite to the direction A (c in FIG. 5). The external shape seen from the direction A shown in FIGS. 3 and 5 and the external shape seen from the direction orthogonal to the direction A (perpendicular to the paper surface) are shown. As described above, when the exciting coil 3 is energized with an oscillator current and the plasma torch 1 is moved in a direction opposite to the bending direction A of the arc due to this energization, the steepness is 1.3 / 4.0. = 0.325. In this way, the steepness is large and the lateral width of the overlay metal is extremely narrow. In this case as well, the melting length spreads in the traveling direction, and in response to this, the floating and escape of the gas component in the molten metal is promoted, and a high-quality build-up without defects can be obtained.

FIG. 8 shows a mode in which the plasma overlaying apparatus of the present invention is used for overlay welding of the peripheral surface of an engine valve.
In this example, the plasma torch 1 was fixed and the valve was rotated at a predetermined speed. When the build-up width (required build-up width) to be formed on the valve was 5.5 mm, the welding conditions were plasma current 51A, powder gas (argon) flow rate 2 /
min, shield gas (argon) flow rate 5 / min, powder feed rate 5 g / min, valve peripheral speed 480 mm / min, arc swing direction is the valve rotation direction, and excitation is performed under the above-mentioned oscillator energization conditions. The coil 3 was energized. As a result, a suitable overlay was obtained.

[0017]

According to the plasma surfacing apparatus of the present invention, it is possible to obtain a surfacing having a relatively small lateral width and a relatively high height and good penetration quality.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of an embodiment of the present invention.

2A and 2B are diagrams showing a positional relationship between the plasma torch 1 and the magnetic pole pieces 2 shown in FIG. 1, FIG. 2A being an enlarged bottom view of the plasma torch 1 and FIG. 2B being an enlarged front view.

FIG. 3 is an enlarged side view of the plasma torch 1 shown in FIG.

4 is a time chart showing an energization waveform of energization to the exciting coil 3 shown in FIG. 1. FIG.

5 is an enlarged view of the tip of the plasma torch 1 shown in FIG. 1 and shows the cross-sectional shape of the arc,
(A) and (c) are enlarged side views of the plasma torch 1,
(B) is an A1-A2 line enlarged sectional view of the arc 57 shown in (a), (d) is A1-A2 of the arc 57a shown in (c).
It is a line expanded sectional view.

6 is a drawing showing an outer shape of a overlay metal obtained by overlay welding with the plasma torch 1 and the base material 59 stationary and in the modes of FIGS. 5 (a) and 5 (c). FIG. (A)
5 (b) are front and side views of the overlay metal obtained in the embodiment of FIG. 5 (a) (without arc bending), and FIGS. 6 (c) and 6 (d) are FIG. FIG. 3 is a front view and a side view of the overlay metal obtained in the mode (c) (there is a bend in the arc).

FIG. 7 is a view showing the outer shape of the overlay metal obtained when the plasma torch 1 is moved to perform overlay welding, and FIGS. 7 (a) and 7 (b) are diagrams of FIG. The front view and the side view of the overlay metal obtained in the mode (a) (without bending of the arc), and (c) and (d) of FIG. 7 are the modes of (c) of FIG. 5 (c). (Bent) and the moving direction of the plasma torch 1 is the same as the bending direction of the arc, front and side views of the overlay metal, and (e) and (f) of FIG. The front view and the side view of the overlay metal obtained in the mode of FIG. 5C (with arc bending) and when the moving direction of the plasma torch 1 is opposite to the bending direction of the arc. It is a figure.

FIG. 8 is a side view showing one mode in which the plasma torch 1 shown in FIG. 1 performs overlay welding on an engine valve.

FIG. 9 is a vertical cross-sectional view of a tip portion of a conventional plasma torch for overlay welding.

FIG. 10 is a vertical cross-sectional view of the tip portion of another conventional plasma torch.

FIG. 11 is a side view of a torch showing a state of overlay welding using a conventional plasma torch.

[Explanation of symbols]

1: Torch head 2: Magnetic pole piece 3: Excitation coil 10: Oscillation control panel 20: Plasma power supply device 30: Powder supply device 31: Powder supply port 51: Electrode 52: Plasma gas 53: Powder 54: Carrier gas 55 : Cooling water 56: Shielding gas 57: Plasma arc column 58: Molten metal 58a: Overlay metal 58b: Penetration part 59: Base material 60: Nozzle member 60a: Powder supply hole 61, 62: Nozzle

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-63-43769 (JP, A) JP-A-63-224877 (JP, A) JP-A-58-378 (JP, A)

Claims (3)

(57) [Claims] 1. A plasma torch, a plasma power source for forming an arc between a main electrode of the torch and a base material, a powder supply means for supplying metal powder into the formed arc, And a drive means for moving at least one of the torch and the base material relative to the other, in a space between the tip of the main electrode of the torch and the base material. The plasma overlaying apparatus, further comprising magnetic flux generating means for generating a magnetic flux having a component orthogonal to the direction along the central axis of the main electrode and the moving direction. 2. The magnetic flux generating means includes a magnetic core having an end face facing the space between the tip of the main electrode of the torch and the base material, an electric coil wound around the magnetic core, and the electric coil. The plasma overlaying apparatus according to claim 1, comprising means for energizing the coil. 3. The plasma overlaying apparatus according to claim 2, wherein the energizing means interrupts the energizing or reverses the energizing direction at a predetermined cycle.