JP2012122124A - Plasma spraying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small plasma spraying device that can stabilize wire feeding when feeding wire to the vicinity of a nozzle opening of a secondary gas nozzle, regardless of a twisting tendency which the wire inherently possesses, without a secondary bending guide member for conducting a secondary bending exceeding the elastic limit of the wire.SOLUTION: The plasma spraying device includes: a primary gas nozzle 10 for forming a primary gas passage 11 along the outer circumference of a cathode 40 to cover the tip of the cathode 40; the secondary gas nozzle 20 arranged outside of the primary gas nozzle 10 and forming a secondary gas passage 21; and a wire passage 50 for feeding the spraying wire W to the vicinity of the nozzle opening 22 of the secondary gas nozzle 20, having a substantially rectangular cross-sectional shape longer in the extension direction of a plasma frame, and bending the wire W within the range not exceeding the elastic limit of the wire W.

Description

  The present invention relates to a plasma spraying apparatus in which a plasma arc is transferred to an electrically conductive wire to generate a plasma flame, and the wire is sprayed while forming a droplet.

  FIG. 6 is a cross-sectional view schematically showing a conventional plasma spraying apparatus. As shown in FIG. 6, a conventional plasma spraying apparatus 90 includes a primary gas nozzle 91 that forms a primary gas passage 91a, a secondary gas nozzle 92 that is disposed outside the primary gas nozzle 91 and forms a secondary gas passage 92a, Electrical conduction for thermal spraying in the vicinity of the cathode 93 disposed substantially on the central axis of the nozzle port 91 b of the primary gas nozzle 91 and the nozzle port 92 a of the secondary gas nozzle 92, the power supply device 94, and the nozzle port 92 a of the secondary gas nozzle 92. The wire guide hole 95 which supplies the property wire W is provided.

  The wire W is supplied obliquely forward from the wire guide hole 95 toward the central axis of the nozzle port 92a. The primary gas ejected from the primary gas passage 91a is connected to the wire W indirectly connected to the anode side of the power supply device 94 via the secondary gas nozzle 92 and the cathode 93 connected to the cathode side of the power supply device 94. Is formed into a plasma flame F by the arc generated between them, and the wire W is ejected as a droplet D. The droplet D is further refined by the secondary gas injected from the secondary gas passage 92a to the front of the secondary gas nozzle 92, further accelerated, and injected onto the workpiece T to form the sprayed coating S. .

  As described above, in the plasma spraying apparatus in which the wire W is sprayed while being formed into droplets by the plasma flame F and the secondary gas flow, the plasma flame F is stably generated and the uniform droplet D is ejected. The tip of the wire W must always be positioned inside the plasma flame F.

  However, in the conventional plasma spraying apparatus, the wire guide hole 95 for supplying the wire W has a circular cross-sectional shape, and in order to avoid catching or clogging due to the distortion wrinkles inherent in the wire W, The aperture is larger than the outer diameter. For this reason, it is difficult to feed the wire W while correcting the twist of the wire W, and the wire W is distorted and repeatedly deviated from the center of the plasma frame F, and the wire cannot be stably supplied to the center of the plasma frame F. Has the problem.

  Therefore, for example, as described in Patent Document 1, a wire is sandwiched between support plates integrated with a plasma arc torch and a straightening guide member that corrects the primary bend and a wire while guiding the wire from the straightening guide member. By providing a secondary bending guide member that performs secondary bending exceeding the elastic limit and supplying the wire, and removing the distortion wrinkles inherent in the wire, the tip of the wire is plasma. Improvements have been made to ensure that the gas flow is always centered and a stable plasma flame is generated.

JP-A-9-308970

  However, when a secondary bending guide member that performs secondary bending exceeding the elastic limit with respect to the wire as described in Patent Document 1 is integrated with the plasma arc torch, the wire feeding force is the secondary bending guide member. Therefore, it becomes excessive to perform the secondary bending beyond the elastic limit to the wire. Therefore, the wire supply mechanism becomes large, and the whole torch tends to be large.

  Therefore, in the present invention, when the wire is supplied in the vicinity of the nozzle opening of the secondary gas nozzle, the wire is subjected to a secondary bending exceeding its elastic limit regardless of the distortion that the wire inherently has. An object of the present invention is to provide a compact plasma spraying apparatus capable of stabilizing wire feeding without providing a secondary bending guide member for performing the above.

  The plasma spraying device of the present invention includes a cathode, a primary gas nozzle that forms a primary gas passage on the outer periphery of the cathode and covers the tip of the cathode, and a secondary gas passage that is disposed outside the primary gas nozzle to form a secondary gas passage. A secondary gas nozzle and a wire passage for supplying a wire for thermal spraying to the vicinity of the nozzle opening of the secondary gas nozzle, and the primary gas nozzle is ejected by an arc generated between the tip of the wire supplied from the wire passage and the cathode. Plasma is formed by converting the primary gas into plasma, forming a plasma flame that is ejected from the primary gas nozzle, and using the tip of the wire as a droplet, and this droplet is ejected onto the workpiece by the secondary gas that is ejected from the plasma flame and the secondary gas nozzle. In a thermal spraying device, the wire passage has a substantially rectangular cross-sectional shape that is long in the extending direction of the plasma frame, and exceeds the elastic limit of the wire. It is intended to provide a range bend the no.

  According to the plasma spraying apparatus of the present invention, the wire is bent in a range that does not exceed the elastic limit, so that the warped wrinkles of the wire are released in the extending direction of the plasma frame, and in a direction perpendicular to the extending direction of the plasma frame. Can be prevented. Note that, even if the position of the tip of the wire is slightly displaced with respect to the extending direction of the plasma flame, the plasma flame does not become unstable because it is positioned on the axis of the plasma flame. Therefore, according to the plasma spraying apparatus of the present invention, it is possible to stably supply the wire to the central portion of the plasma flame.

  Here, it is desirable that the substantially rectangular cross-sectional shape of the wire passage has a width in the short side direction larger in a range of 3% or more and less than 10% than the diameter of the wire. As a result, the warped wrinkles of the wire can be escaped substantially only in the extending direction of the plasma flame, and the positional deviation in the direction perpendicular to the extending direction of the plasma flame can be prevented. If the width in the short side direction is less than 3% larger than the diameter of the wire, there is a possibility that the gap for releasing the warped wrinkle of the wire in the extending direction of the plasma frame will be insufficient, and it will be caught or clogged. . On the other hand, when the width in the short side direction is 10% or more larger than the diameter of the wire, the gap is too large, and the wire warp may escape not only in the extending direction of the plasma frame but also in the perpendicular direction.

  The wire passage has a primary wire passage having a wire outlet formed in the vicinity of the nozzle port of the secondary gas nozzle, and a secondary wire passage for supplying a wire at a predetermined inclination angle to the primary wire passage. is there. As a result, when the wire is fed from the secondary wire passage to the primary wire passage, the wire is bent within a range not exceeding the elastic limit of the wire due to a predetermined inclination angle, and the wire warp is transformed into plasma. It escapes in the extension direction of a flame | frame, and it can prevent the position shift to a right angle direction with respect to the extension direction of a plasma flame | frame.

  At this time, the predetermined inclination angle is desirably 1 to 5 °. As a result, the wire is bent in a range not exceeding the elastic limit of the wire, and the wire can be supplied more stably to the central portion of the plasma frame. If the predetermined inclination angle is less than 1 °, the wire cannot be bent in a predetermined manner, and the wire feed may not be stable. On the other hand, when the predetermined inclination angle exceeds 5 °, there is a possibility that bending in a range exceeding the elastic limit of the wire is given.

  Moreover, it is desirable that the primary wire passage and the secondary wire passage are arranged with a gap of 3 to 10 mm. As a result, a pseudo large curved wire passage can be formed by the primary wire passage, the secondary wire passage, and the gap, and the wire can be bent in a range not exceeding the elastic range. When the gap is less than 3 mm, it is substantially the same as that formed by one primary wire path. On the other hand, if the gap exceeds 10 mm, the effect of bending applied to the wire by the secondary wire passage is diminished, and in this case as well, it is substantially the same as that formed by one primary wire passage.

(1) The wire passage has a substantially rectangular cross-sectional shape that is long in the extending direction of the plasma frame, and gives the wire a bending within a range that does not exceed the elastic limit. Without providing a secondary bending guide member, the distortion wrinkles inherent in the wire are released in the direction of extension of the plasma frame to prevent displacement in the direction perpendicular to the direction of extension of the plasma frame. The wire can be stably supplied to the central portion of the plasma flame.

(2) The substantially rectangular cross-sectional shape of the wire passage is such that the width in the short side direction is larger than the diameter of the wire by 3% or more and less than 10%, so that the wire warp is substantially in the extending direction of the plasma frame. Therefore, it is possible to prevent the displacement in the direction perpendicular to the extending direction of the plasma flame, and to supply the wire more stably to the center of the plasma flame.

(3) A primary wire passage having a wire outlet formed in the vicinity of the nozzle port of the secondary gas nozzle, and a secondary wire for supplying a wire at an inclination angle of 1 to 5 ° with respect to the primary wire passage. By having the passage, the wire is bent in a range not exceeding the elastic limit of the wire, and the wire can be supplied more stably to the central portion of the plasma frame.

(4) The primary wire passage and the secondary wire passage are arranged with a gap of 3 to 10 mm, so that the wire passage has a curved shape that is pseudo-larger than the primary wire passage and the secondary wire passage. And the wire can be bent in a range not exceeding the elastic range.

It is a schematic block diagram of the plasma spraying apparatus in embodiment of this invention. It is a longitudinal cross-sectional view which shows the detail of the principal part of the plasma spraying torch of FIG. FIG. 3 is a view as seen from an arrow A in FIG. 2. It is operation | movement explanatory drawing of the plasma spraying torch of FIG. It is explanatory drawing which shows the cross-sectional shape of a wire channel | path, and the direction of the force which a wire receives. It is sectional drawing which showed the conventional plasma spraying apparatus typically.

  FIG. 1 is a schematic configuration diagram of a plasma spraying apparatus according to an embodiment of the present invention, FIG. 2 is a longitudinal sectional view showing details of a main part of the plasma torch of FIG. 1, FIG. 3 is a view taken along arrow A in FIG. FIG. 2 is an operation explanatory diagram of the plasma torch of FIG. 1.

  In FIG. 1, a plasma spraying apparatus 1 according to an embodiment of the present invention includes a plasma spraying torch 2 that sprays a wire W formed as droplets by a plasma flame onto an object to be processed, and a primary gas and a secondary to the plasma spraying torch 2. A gas supply source 3 for supplying gas, a power supply 4 for supplying operating power to the plasma spraying torch 2, a wire reel 5 around which the wire W is wound, and a winding wrinkle of the wire W drawn from the wire reel 5 are corrected. A wire straightening machine 6 and a wire supply mechanism 7 for supplying the wire W to the plasma spraying torch 2 by a wire feed tube 8 are provided.

  As shown in FIG. 2, the plasma spray torch 2 includes a primary gas nozzle 10 that forms a primary gas passage 11, a secondary gas nozzle 20 that is disposed outside the primary gas nozzle 10 and forms a secondary gas passage 21, and a primary gas nozzle. 10 and the secondary gas nozzle 20 are arranged on substantially the central axes of the tertiary gas nozzle 30 that forms the tertiary gas passage 31 and the nozzle port 12 of the primary gas nozzle 10 and the nozzle port 22 of the secondary gas nozzle 20. A cathode 40 and a wire passage 50 for supplying the wire W for thermal spraying to the vicinity of the nozzle port 22 of the secondary gas nozzle 20 are provided.

  The primary gas nozzle 10 is formed so as to cover the tip of the cathode 40, and the primary gas passage 11 is formed on the outer periphery of the cathode 40. The primary gas supplied to the primary gas passage 11 is an inert gas such as nitrogen gas or argon gas. Alternatively, compressed air can be used as the primary gas. The primary gas supplied by the primary gas passage 11 is injected forward of the secondary gas nozzle 20 from the nozzle port 12 of the primary gas nozzle 10.

  The tertiary gas nozzle 30 is formed so as to wrap the outside of the primary gas nozzle 10, and a tertiary gas passage 31 is formed on the outer periphery of the primary gas nozzle 10. The tertiary gas is a gas such as compressed air or carbon dioxide. The secondary gas nozzle 20 is formed so as to wrap around the outer side of the tertiary gas nozzle 30, and a secondary gas passage 21 is formed on the outer periphery of the tertiary gas nozzle 30. The secondary gas is a gas such as compressed air or carbon dioxide.

  The wire passage 50 includes a primary wire passage 51a having a wire outlet 51b formed in the vicinity of the nozzle port 22 of the secondary gas nozzle 20, and a wire W for supplying the wire W at a predetermined inclination angle θ to the primary wire passage 51a. And a next wire passage 52a. The wire passage 50 gives the wire W a bend in a range not exceeding the elastic limit by the primary wire passage 51a and the secondary wire passage 52a.

  As shown in FIG. 3, the primary wire passage 51 a has a substantially rectangular cross-sectional shape that is long in the extending direction of the plasma frame, and linearly penetrates the primary wire guide member 51 disposed outside the secondary gas nozzle 20. Is formed. Similarly, the secondary wire passage 52a also has a substantially rectangular cross-sectional shape that is long in the extending direction of the plasma frame, and linearly penetrates the secondary wire guide member 52 disposed at a position away from the primary wire passage 51a. Is formed.

  The width a in the long side direction of the primary wire passage 51a is set larger than the diameter d of the wire W in a range of 10% to 95%. Further, the width b in the short side direction of the primary wire passage 51a is set larger than the diameter d of the wire W in a range of 3% or more and less than 10%. In this embodiment, the diameter d of the wire W is 1.6 mm, the width a in the long side direction is about 0.2 to 1.5 mm larger than the diameter d of the wire W, and the width b in the short side direction is the wire It is set larger by 0.05 to 0.15 mm than the diameter d of W. The same applies to the secondary wire passage 52a.

  In addition, the substantially rectangular cross-sectional shape which the primary wire channel | path 51a and the secondary wire channel | path 52a have is C-shaped chamfering, R-chamfering, etc. in the range which the outer surface of the wire W does not contact | connect the corner | angular part of rectangular cross-sectional shape other than rectangular cross-sectional shape. Including shapes that have been processed. Therefore, in this embodiment, the wire W receives only a force in the vertical direction with respect to either the long side plane or the short side plane in the primary wire path 51a and the secondary wire path 52a. Become.

  Further, the inclination angle θ with respect to the primary wire passage 51a of the secondary wire passage 52a is an angle formed by the center line of the primary wire passage 51a and the center line of the secondary wire passage 52a. In the present embodiment, the inclination angle θ is set to about 1 to 5 °. The secondary wire guide member 52 is provided at a position where the primary wire passage 51a and the secondary wire passage 52a are arranged with a gap c therebetween. In the present embodiment, the gap c is set to about 3 to 10 mm.

  Thus, in the plasma spraying torch 2 in the present embodiment, the primary wire passage 51a and the secondary wire passage 52a are arranged with the gap c therebetween, so that the linear primary wire passage 51a and the secondary wire passage 52a are respectively arranged. Thus, a pseudo-curved wire passage 50 is formed, and the wire W is bent in a range not exceeding the elastic range. Note that the primary wire passage 51a and the secondary wire passage 52a may be curved.

  The anode side of the power source 4 is connected to the primary wire guide member 51 and is indirectly connected to the wire W passing through the primary wire passage 51 a of the primary wire guide member 51. On the other hand, the cathode side of the power supply 4 is connected to the cathode 40. Note that the anode side of the power supply 4 may be directly connected to the wire W.

  In the plasma spraying apparatus 1 having the above configuration, when the wire W wound around the wire reel 5 is fed to the plasma spraying torch 2 by the wire supply mechanism 7, the strong curl of the wire W is corrected by the wire straightening machine 6, It is stretched into a gentle curve. Then, the wire W is supplied to the wire passage 50 via the wire feed tube 8. In the wire path 50, the wire W receives only a force in the vertical direction with respect to either the long side plane or the short side plane in the primary wire path 51a and the secondary wire path 52a. As shown in FIG. 4, the bending in the range not exceeding the elastic limit is given in the extending direction of the plasma frame F.

  Here, since the primary wire passage 51 a and the secondary wire passage 52 a have a substantially rectangular cross-sectional shape that is long in the extending direction of the plasma frame F, the warp is released in the extending direction of the plasma frame F. In particular, in the present embodiment, the width b in the short side direction is set to be larger than the diameter d of the wire W in a range of 3% or more and less than 10%. It is not escaped in the right angle direction. Therefore, even if the position of the distal end portion of the wire W is slightly displaced with respect to the extending direction of the plasma frame F, the displacement of the plasma frame F in the direction perpendicular to the extending direction of the plasma frame F is prevented. It will be located on the axis.

  FIG. 5 shows the cross-sectional shape of the wire passage and the direction of the force applied to the wire. In FIG. 5, a substantially rectangular cross section A is a rectangular cross section shape, a substantially rectangular cross section B is a shape in which a corner portion of the rectangular cross section is C-chamfered in a range where the outer surface of the wire W does not contact, and a substantially rectangular cross section C is a rectangular shape. The corner portion of the cross-sectional shape is a shape that has been subjected to R chamfering as long as the outer surface of the wire W does not contact. In these substantially rectangular cross-sectional shapes, regardless of whether the wire W is in contact with the plane in the long side direction or the plane in the short side direction, only the force in the direction perpendicular to each plane is received.

  Since the wire W cannot be completely straightened even by the wire straightening mechanism 7, the warp remains. The wire feed tube 8 is bent into various states and does not have a constant shape due to the handling of the plasma spraying torch 2 during operation. For this reason, when the wire W with the distortion remains in the wire feed tube 8 whose shape is not constant as described above, bending or twisting force acts on the wire W in accordance with the shape of the wire feed tube 8. By this bending or twisting force, the wire W is bent freely like the spring within the elastic limit, and is fed while meandering in the wire feed tube 8 at a position where the direction of the force is stable.

  At this time, in the above-described substantially rectangular cross-sectional shape, when the wire W is in contact with the plane in the short side direction, the direction perpendicular to the plane in the short side direction, that is, the extending direction of the plasma frame F (hereinafter, “X The distortion warp is released in the extending direction of the plasma flame F. When a force in a direction perpendicular to the extending direction of the plasma frame F (hereinafter referred to as “Y direction”) is applied while only in contact with the plane in the short side direction, the wire W Moves freely by the gap of the width b in the short side direction and touches the plane in the long side direction. In this case, too, the force in the vertical direction (Y direction) acts on the plane in the long side direction. The position of is stable. In particular, when a twisting force is applied, the forces in the X direction and the Y direction are distributed to the forces in the short side direction and the long side direction, and the force acts in the direction perpendicular to each surface, causing the wire W to twist. In order to act to suppress, the position of the wire W is stabilized.

  On the other hand, in the case of a round cross section or a long round cross section, when the wire W is in contact with the curved surface of the round cross section or the long round cross section, it receives only a force perpendicular to the curved surface. Can move freely along. In particular, when the twisting force is received, the wire W freely rotates along the curved surface, and thus the twist of the wire W is not suppressed. For this reason, the direction of the force received by the wire W is not determined, and the position of the wire W is indefinite.

  As described above, in the plasma spraying apparatus 1 according to the present embodiment, the tip portion of the wire W can stably supply the wire W to the central portion of the plasma frame F. And the primary gas ejected from the primary gas passage 11 is connected to the anode side of the power supply 4 indirectly via the primary wire guide member 51, and the cathode 40 connected to the cathode side of the power supply 4. The plasma generated by the arc generated during the period becomes a plasma flame F, and the wire W is ejected as a droplet D. The droplet D is further refined by the secondary gas injected from the secondary gas passage 21 to the front of the secondary gas nozzle 20, further accelerated, and injected onto the workpiece T to form the sprayed coating S. .

  At this time, in the plasma spraying apparatus 1 in the present embodiment, the inside of the tertiary gas flow injected from the tertiary gas passage 31 disposed between the primary gas passage 11 and the secondary gas passage 21 is in the plasma flame F. Upon receiving heat, a high-temperature gas jet G is formed. By suppressing the disturbance generated from the outer peripheral portion of the plasma flame F due to the rapid narrowing of the secondary gas injected to the outside by the high-temperature gas jet G, gas diffusion in the plasma flame F can be prevented, Oxidation of the surface of the particles that have become the droplet D is reduced. Thereby, it is possible to form the sprayed coating S with less oxidation on the workpiece T.

  In addition, when nitrogen gas, argon gas, or the like, which is an inert gas, is used as the tertiary gas, the disturbance generated from the outer peripheral portion of the plasma flame F due to the rapid constriction of the secondary gas as described above is prevented. A high-temperature inert gas jet that receives the heat of the plasma flame F is formed on the outer periphery of the plasma flame F. Thereby, the particles of the droplet D are protected from being oxidized by the secondary gas because they are refined and accelerated in a state in which the change in the components of the particles is prevented by high-temperature inert gas injection. Thereby, it becomes possible to form the thermal spray coating S with less oxidation.

  In the present embodiment, both the primary wire passage 51a and the secondary wire passage 52a have a substantially rectangular cross-sectional shape that is long in the extension direction of the plasma frame, but only one of them is in the extension direction of the plasma frame. It is also possible to have a long substantially rectangular cross-sectional shape. In this case, the warp of the wire W is released in the extending direction of the plasma frame F by the primary wire passage or the secondary wire passage having a substantially rectangular cross-sectional shape that is long in the extending direction of the plasma frame, and the tip portion of the wire W is moved to the plasma frame. It can be supplied to the center of F.

  The plasma spraying apparatus of the present invention is useful as an apparatus for forming a rust-proof spray coating on the surface of a steel structure.

DESCRIPTION OF SYMBOLS 1 Plasma spraying apparatus 2 Plasma spraying torch 3 Gas supply source 4 Power supply 5 Wire reel 6 Wire straightening machine 7 Wire supply mechanism 10 Primary gas nozzle 11 Primary gas passage 12 Nozzle port 20 Secondary gas nozzle 21 Secondary gas passage 22 Nozzle port 30 Tertiary gas nozzle 31 Tertiary gas passage 40 Cathode 50 Wire passage 51 Primary wire guide member 51a Primary wire passage 52 Secondary wire guide member 52a Secondary wire passage

Claims (5)

A cathode, a primary gas nozzle that forms a primary gas passage on the outer periphery of the cathode and covers the tip of the cathode, a secondary gas nozzle that is disposed outside the primary gas nozzle to form a secondary gas passage, and the secondary gas nozzle A wire passage for supplying a wire for thermal spraying to the vicinity of the nozzle opening of the gas nozzle, and a primary gas injected from the primary gas nozzle by an arc generated between the tip of the wire supplied from the wire passage and the cathode. Plasma is formed, a plasma flame is ejected from the primary gas nozzle, the tip of the wire is used as a droplet, and the droplet is ejected onto the object to be processed by the secondary gas ejected from the plasma flame and the secondary gas nozzle. In plasma spraying equipment,
The plasma spraying apparatus, wherein the wire passage has a substantially rectangular cross-sectional shape that is long in the extending direction of the plasma frame, and gives the wire a bending that does not exceed an elastic limit.   2. The plasma spraying apparatus according to claim 1, wherein the substantially rectangular cross-sectional shape of the wire passage has a width in a short side direction that is greater than a diameter of the wire by 3% or more and less than 10%.   The wire passage includes a primary wire passage having a wire outlet formed in the vicinity of a nozzle port of the secondary gas nozzle, and a secondary wire passage for supplying the wire at a predetermined inclination angle with respect to the primary wire passage. The plasma spraying apparatus according to claim 1, wherein the plasma spraying apparatus is provided.   The plasma spraying apparatus according to claim 3, wherein the predetermined inclination angle is 1 to 5 °.   The plasma spraying apparatus according to claim 3 or 4, wherein the primary wire passage and the secondary wire passage are arranged with a gap of 3 to 10 mm.

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