COLD SPRAY GUN AND COLD SPRAY APPARATUS EQUIPPED WITH THE SAME

Abstract

The present invention provides a cold spray gun and a cold spray apparatus equipped with the same, which are capable of effectively suppressing clogging of a raw material powder feeding port and operating the cold spray apparatus equipped with the cold spray gun by maintaining a working gas temperature at a high temperature closer to a melting point or a softening point of the raw material powder. In order to achieve the above described object, there is provided a cold spray gun configured to spray out a raw material powder transported by a carrier gas, together with a working gas heated to a temperature equal to or lower than a melting point or a softening point of the raw material powder as a supersonic flow and to cause the raw material powder to collide with a base material in a solid state, thereby to form a coating film.

Claims

1. A cold spray gun configured to spray out a raw material powder transported by a carrier gas, together with a working gas heated to a temperature equal to or lower than a melting point or a softening point of the raw material powder as a supersonic flow and to cause the raw material powder to collide with a base material in a solid state, thereby to form a coating film, the cold spray gun comprising: a chamber containing the working gas; a cold spray nozzle having a working gas flow path formed therein, at an outlet of which the working gas discharged from the chamber is sprayed out as a supersonic flow; a raw material powder feeding flow path that supplies the raw material powder to the working gas discharged from the chamber; and a cooling means for cooling the raw material powder feeding flow path.

2. The cold spray gun according to claim 1, wherein the cooling means simultaneously cools an inner wall constituting the working gas flow path.

3. The cold spray gun according to claim 1, wherein the raw material powder feeding flow path is formed to be inclined toward a downstream side of the working gas flow path.

4. The cold spray gun according to claim 1, wherein the raw material powder feeding flow path is formed to be inclined toward an upstream side of the working gas flow path.

5. The cold spray gun according to claim 1, wherein the cooling means is a water-cooled cooling unit equipped with a coolant flow path through which a coolant circulates.

6. A cold spray apparatus comprising the cold spray gun as claimed in claim 1.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0019] FIG. 1 is a schematic diagram illustrating a schematic construction of a cold spray apparatus according to the present embodiment.

[0020] FIG. 2 is a schematic cross-sectional perspective view of a cold spray gun according to the present embodiment.

[0021] FIG. 3 is a schematic cross-sectional view of the cold spray gun of FIG. 2.

[0022] FIG. 4 is a partially enlarged view illustrating a raw material powder feeding flow path of the cold spray gun according to another embodiment.

DESCRIPTION OF EMBODIMENTS

[0023] The present invention is a cold spray gun configured to spray out a raw material powder transported by a carrier gas, together with a working gas heated to a temperature equal to or lower than a melting point or a softening point of the raw material powder as a supersonic flow and to cause the raw material powder to collide with a base material in a solid state, thereby to form a coating film, the cold spray gun being characterized by being equipped with: a chamber containing the working gas; a cold spray nozzle having a working gas flow path formed therein, at an outlet of which the working gas discharged from the chamber is sprayed out as a supersonic flow; a raw material powder feeding flow path that supplies the raw material powder to the working gas discharged from the chamber; and a cooling means for cooling the raw material powder feeding flow path. Hereinafter, embodiments of the cold spray apparatus using the cold spray gun of the present invention will be described with reference to the accompanying drawings.

[0024] FIG. 1 is a schematic diagram illustrating a schematic construction of a cold spray apparatus C according to the present embodiment. The cold spray apparatus C according to the present embodiment is equipped with: a cold spray gun 1 to which the present invention is applied; a raw material powder feeding device 6 that supplies the raw material powder together with a carrier gas to the cold spray gun 1; and a compressed gas supply unit that supplies a working gas of a specific pressure to the cold spray gun 1 and supplies a carrier gas of a specific pressure to the raw material powder feeding device 6.

[0025] Any compressed gas supply unit may be used as long as the compressed gas supply unit can supply a high-pressure gas to the cold spray gun 1 and the raw material powder feeding device 6. In the present embodiment, a compressed gas cylinder 2 containing high-pressure gas is used as the compressed gas supply unit. Therefore, in the present invention, the compressed gas may be supplied from, for example, a compressor or the like.

[0026] Examples of the gas used as the working gas supplied to the cold spray gun 1 from the compressed gas supply unit and the carrier gas supplied to the raw material powder feeding device 6 may include helium, nitrogen, air, argon, and a mixed gas thereof. Any gas may be selected according to the raw material powder for use in forming the coating film. To achieve a high linear velocity, helium is preferably used.

[0027] In the present embodiment, a gas supply line 3 connected to the compressed gas cylinder 2 branches into a working gas line 4 connected to the cold spray gun 1 and a carrier gas line 5 connected to the raw material powder feeding device 6.

[0028] The working gas line 4 includes a heater 7 serving as a heating device that is an electric resistance heating element, inside of which there is formed a working gas flow path. The working gas line 4 includes a pressure regulator 8 and a flow meter 9, which are used to adjust the pressure and the flow rate of the working gas supplied to the heater 7 from the compressed gas cylinder 2. When a voltage is applied from a power source 10 to the heater 7, resistance heat is generated by energization to heat a working gas passing through the working gas flow path formed therein, to a specific temperature equal to or lower than a melting point or a softening point of the raw material powder. In the present embodiment, a heater that is an electric resistance heating element is used as the working gas heating device, but the present invention is not limited to this. Any device may be used as long as the device can heat the working gas under high pressure to a specific temperature equal to or lower than a melting point or a softening point of the raw material powder. An outlet of the working gas line 4 is connected to a chamber 21 of the cold spray gun 1.

[0029] An end portion of the carrier gas line 5 is connected to the raw material powder feeding device 6. The raw material powder feeding device 6 is equipped with: a hopper 11 containing the raw material powder; a measure 12 for measuring the raw material powder supplied from the hopper 11; and a raw material powder feeding line 13 for feeding the measured raw material powder together with the carrier gas supplied from the carrier gas line 5 into the chamber 21 of the cold spray gun 1. The carrier gas line 5 includes a pressure regulator 16, a flow meter 17, and a pressure gauge 18, which are used to adjust the pressure and the flow rate of the carrier gas supplied to the raw material powder feeding device 6 from the compressed gas cylinder 2.

[0030] Examples of the raw material powder used in the present invention may include metals, alloys, and intermetallic compounds. More specific examples of the raw material powder may include nickel, iron, silver, chromium, titanium, copper, or an alloy thereof.

[0031] Next, the cold spray gun 1 as an embodiment of the cold spray gun according to the present invention will be described in detail with reference to FIGS. 2 and 3. FIG. 2 is a cross-sectional perspective view of the cold spray gun 1 according to the present embodiment. FIG. 3 is a schematic cross-sectional view of the cold spray gun 1 of FIG. 2.

[0032] The cold spray gun 1 is equipped with: a main body 20 defining a chamber 21 containing a high-pressure working gas thereinside; a cold spray nozzle 30 connected to a distal end of the chamber 21; a raw material powder feeding flow path 40 that supplies the raw material powder to the working gas discharged from the chamber 21; and a cooling means for cooling at least the raw material powder feeding flow path 40.

[0033] The main body 20 is constituted by a bottomed cylindrical piece having a pressure resistance capable of withstanding a high pressure of, for example, 3 MPa to 10 MPa. The main body 20 is preferably made of a stainless alloy or a nickel-based heat-resistant alloy. A working gas inlet 22 is formed in a bottom portion of this main body 20. The working gas inlet 22 is connected to an outlet of the working gas line 4 through a working gas feeding nozzle 23, from which the working gas heated by the heater 7 flows out. A chamber outlet 24 is formed in the main body 20 of the present embodiment. A nozzle connection portion 25 for connecting the cold spray nozzle 30 is integrally formed at a distal end of the chamber outlet 24. Note that in the drawing, reference numeral 28 denotes a rectifying plate for rectifying a working gas flow in the chamber 21 so as not to be turbulent.

[0034] The cold spray nozzle 30 is equipped with: a compression unit 32 formed in a tapered conical shape from a nozzle inlet 31 at the distal end over an extending direction; a narrow throat portion 33 continuing to the compression unit 32, and an expansion portion 34 formed in a divergent conical shape extending from the throat portion 33 to a nozzle outlet 35 at the other end. The compression unit 32, the throat portion 33, and the expansion portion 34 constitutes the working gas flow path 36 extending from the nozzle inlet 31 to the nozzle outlet 35.

[0035] The cold spray nozzle 30 may be made of stainless steel, tool steel, cemented carbide alloy, or the like. However, if nickel, copper, aluminum, stainless steel, or an alloy thereof is used as the raw material powder, the raw material powder may adhere to a portion of the nozzle, especially the expansion unit, and further the nozzle may be clogged. Thus, at least the inner wall surface of the cold spray nozzle 30 is preferably made of a glass material, a ceramic material, a tungsten carbide alloy, or the like. The glass material as used herein is not particularly limited, and examples thereof may include silicate glass, alkali silicate glass, soda lime glass, potash lime glass, lead glass, barium glass, and borosilicate glass, but abrasion-resistant glass, specifically silicate glass or alkali silicate glass is preferred. Further, examples of the ceramic material may include silicon nitride ceramics, zirconia ceramics, and silicon carbide ceramics. Note that in the present invention, the material and shape of the cold spray nozzle 30 are not limited to the material and shape described herein, and an existing cold spray nozzle may be employed.

[0036] The raw material powder feeding flow path 40 supplies the raw material powder to the working gas after being discharged from the chamber 21 of the main body 20 described above, more preferably to the working gas before flowing into the throat portion 33 of the cold spray nozzle 30. In the present embodiment, the raw material powder feeding flow path 40 is provided on a downstream side of the chamber outlet 24 of the nozzle connection portion 25 of the main body 20 and in the throat portion 33 of the cold spray nozzle 30, more preferably on an upstream side of the nozzle inlet 31.

[0037] In the present embodiment, the raw material powder feeding flow path 40 is formed in a raw material powder flow path forming part 41 located in the nozzle connection portion 25 of the main body 20. Like the main body 20, the raw material powder flow path forming part 41 is preferably made of a stainless alloy or a nickel-based heat-resistant alloy having a pressure resistance capable of withstanding a high pressure of 3 MPa to 10 MPa. One end of the raw material powder feeding flow path 40 is connected communicating with a raw material powder feeding nozzle 42 provided in the nozzle connection portion 25. This raw material powder feeding nozzle 42 is connected to the above described raw material powder feeding line 13. The other end of the raw material powder feeding flow path 40 is opened in a flow path formed in the nozzle connection portion 25 through which the working gas flows or in a working gas flow path 36 of the cold spray nozzle 30.

[0038] In the present invention, the raw material powder feeding flow path 40 may be connected from a direction substantially perpendicular to a working gas flow direction from the chamber outlet 24 to the throat portion 33 of the cold spray nozzle 30 to supply the raw material powder from the direction substantially perpendicular to the working gas flow direction, but may be formed with a specific inclination angle with respect to the working gas flow direction.

[0039] Specifically, in the embodiment illustrated in FIG. 3, the raw material powder feeding flow path 40 is formed to be inclined with a specific inclination angle toward the downstream side of the working gas flow path 36. This configuration can shorten a contact time during which the raw material powder to be supplied to the working gas is in contact with the working gas than a configuration of supplying the raw material powder from the direction substantially perpendicular to the working gas flow direction, and can suppress an increase in temperature of the raw material powder. In contrast, in another embodiment illustrated in FIG. 4, the raw material powder feeding flow path 40 is formed to be inclined at a specific angle toward the upstream side of the working gas flow path 36. This configuration can longer the contact time during which the raw material powder to be supplied to the working gas is in contact with the working gas than a configuration of supplying the raw material powder from the direction substantially perpendicular to the working gas flow direction. Therefore, the raw material powder of a high melting point, such as titanium, tantalum, and Inconel (trademark) can be heated to a high temperature near the melting point. Therefore, the contact time during which the raw material powder to be supplied to the working gas is in contact with the working gas can be adjusted by using a raw material powder flow path forming part 41 selected from a plurality of raw material powder flow path forming parts 41 in which the raw material powder feeding flow path 40 is formed at a different inclination angle with respect to the working gas flow direction.

[0040] The cold spray gun 1 according to the present invention is equipped with at least the cooling means for cooling the raw material powder feeding flow path 40 as described above. The cooling means is preferably a water-cooled cooling unit 45 equipped with a coolant flow path 46 through which a coolant circulates. In the present embodiment, the coolant flow path 46 is provided in the raw material powder flow path forming part 41 constituting the raw material powder feeding flow path 40 or at a position where heat can be exchanged with the raw material powder flow path forming part 41. The water-cooled cooling unit 45 constituting the cooling means of the present invention preferably cools the raw material powder feeding flow path 40 and at the same time cools at least an inner wall surface 36A of the working gas flow path 36 of the cold spray nozzle 30.

[0041] Specifically, in the present embodiment, the water-cooled cooling unit 45 is equipped with: a series of coolant flow paths 47 formed between a plurality of flow path forming parts 48 to 50 and the cold spray nozzle 30 inside of which there is formed a working gas flow path 36; and a coolant flow path 46 for cooling the above described raw material powder feeding flow path 40. A coolant flow path 47 is formed between a flow path forming part 48 and an outer peripheral surface of the cold spray nozzle 30. A flow path forming part 49 and a flow path forming part 50 are disposed between the nozzle connection portion 25 of the main body 20 and the cold spray nozzle 30 to form the coolant flow path 47 between the nozzle connection portion 25 and the cold spray nozzle 30. The coolant flow path 47 for cooling the inner wall surface of the cold spray nozzle 30 and the coolant flow path 46 for cooling the raw material powder feeding flow path 40 preferably constitute a series of cooling paths. The coolant flowing through the coolant flow paths 46 and 47 is more preferably a countercurrent flow with respect to the flow direction of the working gas flowing through the working gas flow path 36 of the cold spray nozzle 30. This is because the countercurrent flow can efficiently cool the inner wall surface 36A of the working gas flow path 36 through which the working gas flows, and thereby can effectively suppress the adherence of the raw material powder. Note that, in the present invention, the coolant for use in the water-cooled cooling unit 45 is not particularly limited, but for example, cooling water may be used. Note also that in the present embodiment, the cooling means is a water-cooled cooling unit, but the cooling means is not limited to this and any unit may be used as long as the unit can cool at least the raw material powder feeding flow path 40.

[0042] With the construction described thus far, an operation of forming a coating film by using the cold spray apparatus C according to the present embodiment will be described. First, a high-pressure working gas is sent to the heater 7 through the gas supply line 3 and the working gas line 4 from the compressed gas cylinder 2 as the high-pressure gas supply unit. Then, the working gas flowing into the heater 7, in the process of passing through the heater 7, is heated to a specific high temperature equal to or lower than a melting point or a softening point of the raw material powder for use in forming the coating film, and then is sprayed into the chamber 21 through the working gas feeding nozzle 23.

[0043] Meanwhile, a high-pressure carrier gas is supplied to the raw material powder feeding device 6 from the compressed gas cylinder 2 as the high-pressure gas supply unit through the gas supply line 3 and the carrier gas line 5. While entraining a specific amount of raw material powder measured by the measure 12 of the raw material powder feeding device 6, the high-pressure carrier gas flows into the raw material powder feeding nozzle 42 provided in the cold spray gun 1 through the raw material powder feeding line 13. The raw material powder feeding flow path 40 connected to the raw material powder feeding nozzle 42 is opened toward the working gas flow path extending from the chamber outlet 24 to the throat portion 33 of the cold spray nozzle 30. Therefore, the carrier gas carrying the raw material powder is supplied to a high-speed working gas flow sprayed out from the chamber outlet 24.

[0044] The high-speed working gas flow carrying the raw material powder supplied from the raw material powder feeding flow path 40 passes through the throat portion 33 from the compression unit 32 of the cold spray nozzle 30 becomes a supersonic flow, and further is sprayed from the nozzle outlet 35 located at the distal end of the expansion portion 34 formed in a divergent conical shape. The raw material powder sprayed from the cold spray nozzle 30 collides with a surface of a base material 60 in a solid state and accumulates to form a coating film 61.

[0045] At this time, the raw material powder flow path forming part 41 forming the raw material powder feeding flow path 40 is equipped with a coolant flow path 46 through which a coolant circulates. Therefore, even if the cold spray nozzle 30 is heated by the working gas flow, the raw material powder feeding flow path 40 can always maintain a low temperature without being heated to a specific high temperature equal to or lower than a melting point or a softening point of the raw material powder. Thus, the raw material powder in the raw material powder feeding flow path 40 can be effectively suppressed from being heated to a high temperature by the working gas, and the raw material powder in the raw material powder feeding flow path 40 can be always maintained at a low temperature. Thus, even if the metal powder used as the raw material powder contacts and adheres to a high-temperature metal at a temperature considerably lower than the melting point, the metal powder can be maintained at a low temperature until just before joining the working gas by the water-cooled cooling unit 45. Thus, such a disadvantage can be effectively suppressed that the raw material powder clogs the raw material powder feeding flow path 40. Therefore, the working gas temperature can be set to a temperature closer to a melting point or a softening point of the raw material powder without considering the clogging of the raw material powder flow path, and a dense and high-quality coating film can be formed with a high adhesion efficiency.

[0046] Further, as described above, the coolant flow path 46 for cooling the raw material powder feeding flow path 40 is equipped with the cold spray nozzle 30, inside of which the working gas flow path 36 is formed; the coolant flow path 47 formed between itself and a flow path forming part 50; and the water-cooled cooling unit 45 constituting a series of coolant flow paths. Thus, by circulating a coolant in the water-cooled cooling unit 45, the raw material powder feeding flow path 40 can be cooled, and at the same time the inner wall surface 36A of the working gas flow path 36 of the cold spray nozzle 30 can also be cooled. Thus, the inner wall surface 36A of the working gas flow path 36 through which the working gas flows can also be efficiently cooled, which can effectively suppress a disadvantage that the raw material powder adheres to the inner wall surface 36A of the working gas flow path 36 on a downstream side of the raw material powder feeding flow path 40.

INDUSTRIAL APPLICABILITY

[0047] The cold spray gun and the cold spray apparatus according to the present invention can effectively suppress a disadvantage that the raw material powder is heated by a high-temperature working gas in the raw material powder supply path and adheres to the inner wall, causing clogging. Thus, the working gas temperature can be set to a high temperature closer to a melting point or a softening point of the raw material powder without considering the clogging of the raw material powder in the raw material powder supply path. Therefore, a dense and high-quality coating film can be formed with a higher adhesion efficiency than before.

REFERENCE SIGNS LIST

[0048] C cold spray apparatus [0049] 1 cold spray gun [0050] 2 compressed gas cylinder (high-pressure gas supply unit) [0051] 3 gas supply line [0052] 4 working gas line [0053] 5 carrier gas line [0054] 6 raw material powder feeding device [0055] 7 heater [0056] 13 carrier gas line [0057] 20 main body [0058] 21 chamber [0059] 22 working gas inlet [0060] 23 working gas feeding nozzle [0061] 24 chamber outlet [0062] 25 nozzle connection portion [0063] 30 cold spray nozzle [0064] 31 nozzle inlet [0065] 32 compression unit [0066] 33 throat portion [0067] 34 expansion portion [0068] 35 nozzle outlet [0069] 36 working gas flow path [0070] 36A inner wall surface [0071] 40 raw material powder feeding flow path [0072] 41 raw material powder flow path forming part [0073] 42 raw material powder feeding nozzle [0074] 45 water-cooled cooling unit [0075] 46, 47 coolant flow path [0076] 60 base material [0077] 61 coating film