JPH10183328A - Arc thermal spraying method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an arc thermal spraying method by preventing a bridging phenomenon of a fused metal ion accordance with Fleming's left hand rule so as to stably maintain an arc when increasing its melting quantity and significantly improve a thermal spraying efficiency. SOLUTION: Assuming that an electric current is caused to flow inside a fused metal in a bridged state from an upper side wire 7 to a lower side wire 7', by giving a magnetic field (arrow mark 18) in the direction orthogonal to a face including plural wires (direction orthogonal to paper face), a fused metal 13, in accordance with Fleming's left hand rule, receives electromagnetic force (arrow mark 19) in the right direction in the figure (object direction), and as combined with dynamic pressure of the gas injected from a tube 6, a fused metal is quickly separated from the wires 7, 7'.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an arc spraying method, and particularly to decoration, anticorrosion, or a conductive film, an electrode, a catalyst film,
The present invention relates to an arc spraying method for imparting physical and chemical properties such as a filter, or an arc spraying method applied to a metal powder manufacturing apparatus using an arc.

[0002]

2. Description of the Related Art Arc spraying is a technique in which two wires are used as electrodes, an arc is generated between the tips, and the wires are melted and blown off simultaneously with a compressed gas jet to form a coating. A conventional technique of the arc spraying method will be described with reference to FIGS. 5A is a plan view of the arc spraying torch, FIG. 5B is a front view, and FIG. 6 is a side view, and the reference numerals, names, and functions of members are used in common with the later-described embodiments. Reference numeral 1 denotes a torch housing cut out so that the inside can be seen. 1 'is a mount part made of an insulating material which is a part of the torch housing, 2' is a power supply chip fixed to the mount part 1 ', 3' is a driving roller, 4 and 4 'are driven rollers, Reference numeral 5 denotes a motor fixed to the torch housing 1, and the driven rollers 4, 3 'are driven and rotated while driving the driving rollers 3, 3'.
The wire 7 and 7 'are fed together with 4'. 6 is a pipe fixed to the mount portion 1 'for ejecting compressed gas,
7, 7 'is a wire formed by spraying the material into a wire shape;
8 'is a wire reel installed separately from the torch, 9 is an arc power supply for applying an arc voltage to the power supply tip, 10 is a compressed gas cylinder, and 11 is a handle which is a part of the torch housing.

In such an apparatus, a wire reel 8,
Wires 7 and 7 ′ from 8 ′ are squeezed and transported by driving rollers 3 and 3 ′ driven by a motor 5 and driven rollers 4 and 4 ′ and guided to feeding chips 2 and 2 ′. Intersect. At this time, when electric power is supplied to the wires 7, 7 'via the power supply chips 2, 2' by the arc power supply 9, an arc is generated at the wire intersection. Since the wire is sequentially melted by the arc heat, the arc can be maintained by selecting an appropriate power and wire supply speed. At this time, the gas cylinder 1 is connected by the pipe 6.
When a compressed gas from 0 is blown from the mount 1 'side to the arc at the wire intersection, the molten metal flies forward as molten droplets and deposits on the surface of the object to form a sprayed layer.

The details of the droplet formation will be described with reference to FIG.
FIG. 7 is an operation diagram for explaining the present invention, and reference numerals 18 and 19 are used for explaining the operation of the present invention described later. FIG.
In the figure, 6 is a pipe, and 7 and 7 'are wires, all of which are the same as those shown in FIGS. 5 (A), 5 (B) and 6. 12, 1
2 ′ is a molten metal formed at the tip of the wire 7, 7 ′, 1
3 is the molten metal bridging the wires 7, 7 ', 1
Reference numeral 4 denotes a droplet which is flying away from the wires 7 and 7 ', 15 denotes a sprayed film deposited on the surface of the target object, 16 schematically shows an arc generated between the wires 7 and 7', and 17 denotes an arc generated between the wires 7 and 7 '. An arrow 20 indicating the direction of the current flowing in the molten metal 13 in the bridge state is an object to be sprayed.

[0005]

In such a configuration,
In the prior art, the tips of the wires 7, 7 'are melted by the heat of the arc 16 generated between the wires 7, 7', and the molten metal 12, 12 'is formed. The pipe 6
The droplets 14 are forcibly formed by blowing off the compressed gas from the nozzle, and the kinetic energy is applied to the droplets to increase the adhesion between the thermal sprayed film 15 and the object 20 and to reduce the adhesive force in the thermal sprayed film 15. Attempts to achieve reduced porosity.

However, the flow of the compressed gas from the pipe 6 becomes turbulent due to the presence of the wires 7 and 7 ′ and the unsteady arc 16 in the flow path, so that the molten metal 12 and 1 are stably formed.
2 'could not be blown away. In particular, when a large current is passed to increase the efficiency and the amount of melting is increased by increasing the wire supply speed, the molten metal becomes in a bridging state between the wires 7 and 7 'as shown in FIG. Since the electric short circuit occurred, the arc disappeared and the thermal spraying became impossible. For this reason, the efficiency of arc spraying is limited, the construction time is long, and the cost is extremely high.

The present invention has been made in view of the above technical problems, and by preventing the bridging phenomenon of the molten metal, it is possible to stably maintain the arc even when the amount of the molten metal is increased, and to improve the efficiency of the thermal spraying. The purpose is to provide a possible arc spraying method.

[0008]

According to the present invention, as shown in FIG. 7, a magnetic field 18 is applied in a direction perpendicular to the direction of current flow (arrow 17), and a bridge is formed between the wires 7, 7 '. By generating an electromagnetic force (arrow 19) in the molten metal 13, the molten metal 13 is quickly separated from the wire, and the extinction of the arc is prevented to stabilize the thermal spraying. That is, according to the first aspect of the present invention, a voltage is applied to a plurality of, for example, two, metal wires 7 and 7 ', and the metal wires 7 and 7' are supplied so as to intersect at a fixed angle on the tip side, and an arc is provided near the tip intersection. In a so-called arc spraying method, in which a molten metal is sprayed on an object using compressed air or another gas flow to form a coating, a plurality of arcs are generated for the arc generated near the tip intersection. , For example, 2
It is characterized in that a magnetic field is applied in a direction substantially perpendicular to the plane including the wires 7, 7 ', and an electromagnetic force is applied to the molten metal toward the object. In order to smoothly achieve the present invention, it is preferable that the number of wires is two as described in Examples below. However, any material that can apply a magnetic field in a direction substantially perpendicular to a plane including a plurality of wires is preferable. The number is not necessarily limited to two, but may be three.

According to a second aspect of the present invention, a magnetic flux density of a magnetic field applied near the tip intersection and / or an arc flowing between a plurality of metal wires in order to obtain the effect of separating the molten metal more smoothly. It is characterized in that the current is changed almost periodically in a pulse shape or a sine wave shape. That is, specifically, the magnetic field applying means is an electromagnet, and means for changing the current flowing through the electromagnet at a constant cycle, or a permanent magnet or an electromagnet is used to apply a magnetic field having a constant magnetic flux density, and the arc current is applied. Means to change at regular intervals,
Further, the magnetic field applying means is an electromagnet, and the current flowing through the electromagnet is changed at a constant cycle, and almost any of the means for changing the arc current at a constant cycle. It is better to take.

The operation of the invention will be specifically described. In FIG. 7, the inside of the molten metal 13 in the bridge state
Assuming that a current flows from the upper wire 7 to the lower wire 7 ', a magnetic field (arrow 18) is applied in a direction perpendicular to a plane including a plurality of wires, that is, in a direction perpendicular to the plane of FIG. In accordance with the so-called Fleming's left-hand rule, the molten metal 13 receives an electromagnetic force (arrow 19) in the rightward direction (toward the object) in the figure, and is combined with the dynamic pressure of the gas ejected from the pipe 6 to generate the wire 7 , 7 ′, the molten metal is quickly released. Therefore, if the bridging phenomenon of the molten metal can be prevented by the present invention, the arc can be stably maintained even when the amount of melting is increased, and the spraying efficiency can be improved. Incidentally, in FIG.
2 ′ is a molten metal formed at the tip of the wire 7, 7 ′, 1
3 is the molten metal bridging the wires 7, 7 ', 1
4 is a droplet in flight, 15 is a sprayed film, 16 is an arc, 17
Is an arrow indicating the direction of the current flowing through the molten metal 13;
Is an arrow indicating the direction of the magnetic field, 19 is an arrow indicating the direction of the electromagnetic force applied to the molten metal 13, and 20 is an object to be sprayed.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be illustratively described in detail below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the constituent members described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, and are merely described. It is only an example.

1 (A), 1 (B) and 2 show an arc spraying torch according to an embodiment of the present invention. FIG. 1 (A) is a plan view of the arc spraying torch, and FIG. 1 (B) is a front view. FIG. 2 is a side view. In the figure, reference numerals 1 to 11 have the same names and functions as those described in FIG. 5 and FIG. However, in this embodiment, the power supply 9 is a DC power supply, and the upper power supply chip 2 is wired positive and the lower power supply chip 2 'is wired negative. As shown in FIG. 1 (A), a pair of horseshoe-shaped permanent magnets 21 are arranged so as to sandwich the arc generating point at the intersection of the tip of the wire from above and below, as shown in FIGS. 1 (B) and 2. Thus, the upper part is magnetized to the N pole and the lower part is magnetized to the S pole. Reference numerals 22 and 22 'denote magnet mounts which are part of the mount 1'.

1 and FIG. 2, the wires 7, 7 'from the wire reels 8, 8' are driven by motors 5 to drive rollers 3, 3 'and driven rollers 4, 4'. Feeding chips 2, 2 '
And cross each other in front. At this time, as shown in FIG. 7, when power is supplied from the power supply 9 to the wires 7, 7 'via the power supply chips 2, 2', an arc is generated at the intersection of the wire ends, and the wires 7, 7 'are formed. 'Melts, but
As described above, there is a possibility that a phenomenon that the molten metal bridges between the two wires may occur due to a large amount of the molten metal.

However, in the present embodiment, as shown by an arrow 17 in FIG.
A current flows from the side to the wire 7 'side. At this time, the magnetic field from the N pole to the S pole of the permanent magnet 21 penetrates the molten metal from the top to the bottom as shown by the arrow 18, and the molten metal 13 is moved rightward in FIG. direction)
Receiving the electromagnetic force 19 from the wire, easily separates from the wire in combination with the dynamic pressure of the compressed gas. Therefore, the arc can maintain stable thermal spraying without disappearing.

Therefore, according to this embodiment, the molten metal 13 near the intersection of the tip of the wire causes the electromagnetic force 19 toward the object side.
As a result, since the wire is easily detached from the wire in combination with the dynamic pressure of the compressed gas, even if the amount of wire melted is increased, stable thermal spraying is possible, and the efficiency of thermal spraying can be dramatically improved. In addition, since the flying speed of the droplet increases, the degree of adhesion between the sprayed film and the object can be improved, and the porosity in the sprayed film can be reduced.

In the above embodiment, the permanent magnet 21
Is used, a magnetic field having a constant magnetic flux density is energized in a fixed direction, and the arc current is also the DC power supply 9, so that the arc current is also substantially constant. However, in order to obtain the effect of separating the molten metal more smoothly, the magnetic flux density of the magnetic field applied near the tip intersection or / and the arc current flowing between the two metal wires are substantially cycled in a pulse shape or a sine wave shape. As described above, it is clear that the energizing direction of the electromagnetic force 19 formed by the magnetic field and the current must not change in the opposite direction from the object side direction. It is.

Therefore, when a magnetic field having a constant magnetic flux density is energized in a fixed direction by using the permanent magnet 21 as described above, as shown in FIG. Alternatively, the power supply chip 2 applies a sine wave voltage superimposed with a DC component and swinging from zero to only the positive side,
It may be applied to the wires 7, 7 'via 2'. (FIG. 8
(See (A) and (B))

FIGS. 3A, 3B and 4 show an arc spraying torch according to another embodiment of the present invention.
Is a plan view of the arc spraying torch, FIG. 3B is a front view, and FIG. 4 is a side view. In the figure, reference numerals 1 to 11 correspond to FIG.
Also, the names and functions are the same as those described in FIG. As shown in FIG. 1 (A), reference numeral 23 denotes an electromagnet arranged so as to sandwich an arc generating point at an intersection of the tip of the wire from above and below, and 24 denotes an electromagnet controller.
The electromagnet is configured to be capable of applying a control voltage to be described later. 2
Reference numerals 5 and 25 'denote electromagnet mounts which are a part of the mount 1'.

The electromagnet controller 24 can have a function of switching the polarity of the electromagnet 23 in accordance with the polarity of the power supply 9, and a function of generating a pulse waveform, a sine waveform (AC waveform) current, and the like. Therefore, when the power supply 9 is an AC power supply, by switching the polarity of the electromagnet 23 in accordance with the polarity, the molten metal is always directed to the right (in the direction of the object) in the figure.
Can be given. That is, when the upper power supply chip 2 is positive and the lower power supply chip 2 'is negative, as shown in FIG. 7, the polarity of the electromagnet may be controlled so that the magnetic field penetrates the paper from top to bottom, and vice versa. When the upper power supply chip 2 is negative and the lower power supply chip 2 'is positive, the polarity of the electromagnet may be controlled so that the magnetic field penetrates the paper of FIG.

This point will be described with reference to FIGS. 8 (C) and 8 (D). When the power supply 9 is an AC power supply that swings positively and negatively, the electromagnet controller 24 matches the positive and negative (N , S) may be applied. When the power supply 9 is a DC power supply, as shown in FIGS. 8E and 8F, the electromagnet controller 24 outputs a pulse waveform swinging only to the N pole side or a sine waveform (DC component superimposed). (AC waveform). As a result, the biasing direction of the electromagnetic force 19 formed by the magnetic field and the current does not change from the direction toward the object to the opposite direction.

Since the electromagnetic force is given by the product of the value of the current flowing through the molten metal and the magnetic field strength (magnetic flux density), if a pulse waveform current or a sine waveform current is applied to the electromagnet, the electromagnetic force changes periodically. By detaching the droplets at a constant cycle, the droplet detachment phenomenon becomes more stable, and a high thermal spraying efficiency and a sound thermal spray film can be obtained. Further, if the current flowing through the molten metal and the current flowing through the electromagnet are changed in synchronization with each other, the change in the electromagnetic force can be further increased, so that the droplet detachment phenomenon can be more reliably controlled. .

[0022]

As described above, according to the present invention, the bridging phenomenon of the molten metal is prevented according to the so-called Fleming's left-hand rule, so that the arc can be stably maintained even when the amount of melting is increased. Not only can the efficiency of spraying be dramatically improved, but also the flying speed of the droplets increases, so that the degree of adhesion between the sprayed film and the target object and the porosity in the sprayed film are reduced. You.

[Brief description of the drawings]

FIG. 1 shows an arc spraying torch according to an embodiment of the present invention, (A) is a plan view of the arc spraying torch, and (B) is a front view.

FIG. 2 is a side view of FIG.

FIG. 3 shows an arc spraying torch according to an embodiment of the present invention, wherein (A) is a plan view of the arc spraying torch, and (B) is a front view.

FIG. 4 is a side view of FIG. 3;

FIG. 5 shows an arc spraying torch according to the prior art;
(A) is a top view of an arc spraying torch, (B) is a front view.

FIG. 6 is a side view of FIG. 5;

FIG. 7 is a detailed explanatory view showing the operation of droplet formation according to the present invention.

8 (A) to 8 (F) show the relationship between an arc power supply and a magnetic field so that the energizing direction of the electromagnetic force formed by the magnetic field and the electric field does not change from the object side direction to the opposite direction. It is a waveform diagram shown.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Torch housing 2, 2 'Power supply chip 3, 3' Driving roller 4, 4 'Follower roller 5 Motor 6 Pipe 7, 7' Wire 8, 8 'Wire reel 9 Power supply 10 Gas cylinder 11 Handle 12, 12' Wire 7, Molten metal formed at the tip of 7 '13 Molten metal bridged to wires 7 and 7' 14 Droplets in flight 15 Sprayed film 16 Arc 17 Arrow indicating the direction of current flowing in molten metal 13 18 Magnetic field Arrow 19 indicating the direction of the electromagnetic force received by the molten metal 20 object to be sprayed 21 horseshoe-shaped permanent magnet 22, 22 'magnet mounting base 23 electromagnet 24 electromagnet controller 25 electromagnet mounting base

Continuing from the front page (72) Inventor Yasuyuki Takeda 5-717-1 Fukahori-cho, Nagasaki-shi Mitsubishi Heavy Industries, Ltd. Nagasaki Research Laboratory Co., Ltd. (72) Inventor Hideharu Kobayashi 5-717-1, Fukahori-cho, Nagasaki-shi Mitsubishi Heavy Industries shares Nagasaki Research Laboratory

Claims (3)

[Claims] An arc is generated in the vicinity of the tip intersection of a plurality of metal wires to which a voltage has been applied, and a metal melted by the arc is sprayed on an object using compressed air or another gas flow to form a coating. In the arc spraying method to be formed, a magnetic field is applied in a direction substantially perpendicular to a plane including a plurality of wires to an arc generated in the vicinity of the tip intersection, and an electromagnetic force is applied to the molten metal toward an object. An arc spraying method characterized by applying. 2. The arc spraying according to claim 1, wherein the magnetic flux density of a magnetic field applied near the tip intersection and / or the arc current flowing between the plurality of metal wires is changed substantially periodically. Method. 3. The magnetic field applying means is an electromagnet, and means for changing a current flowing through the electromagnet at a constant cycle, or a permanent magnet or an electromagnet applies a magnetic field having a constant magnetic flux density and reduces the arc current to a constant value. Means for changing at a period, Further, the magnetic field applying means is an electromagnet, and while changing the current flowing through the electromagnet at a constant cycle, and substantially in synchronization with this, the means for changing the arc current at a constant cycle The arc spraying method according to claim 2, wherein any one of the means is adopted.