JP7255291B2 - Deposition method - Google Patents

Description

The present invention relates to a film forming method using a cold spray method.

There is known a method for manufacturing a sliding member in which a valve seat having excellent high-temperature wear resistance is formed by spraying raw material powder such as metal on the seating portion of an engine valve by a cold spray method ( Patent document 1).

WO 2017/022505 pamphlet

Automobile engines are equipped with a plurality of intake valves and exhaust valves due to multivalve. Therefore, when the valve seats are formed on the seating portions of a plurality of valves by the cold spray method, the cylinder head and the nozzle of the cold spray device are moved relative to each other, and the plurality of seating portions and the nozzles are sequentially moved. In addition to facing the nozzle, it is necessary to discharge and spray the raw material powder from the nozzle to the seat facing the nozzle.

When the injection of raw material powder is interrupted, the cold spray apparatus requires a waiting time of several minutes until the raw material powder can be stably sprayed again. Therefore, it is desirable that the injection of the raw material powder is continued as much as possible without interruption. However, when forming one valve seat film, the nozzle and the cylinder head are moved relative to each other so as to draw a 360° circle. A turning point at which the moving speed of the nozzle becomes zero may occur at the start point or the film formation end point.

Here, in the trajectory where the turning point occurs in the first layer of the lap portion, the end slope of the film formation starting point of the first layer becomes steep, and when the second layer is injected here, the flattening of the raw material powder is hindered and the sparseness occurs. It becomes a thin film.

The problem to be solved by the present invention is to provide a cold spray film forming method capable of suppressing the formation of a sparse film.

In the present invention, a coating is formed on a film-forming portion while a film-forming portion and a nozzle are relatively moved along a film-forming trajectory, and raw material powder supplied from a raw material powder supply portion is injected from the nozzle. In the film formation method, the raw material powder supply unit is configured to include a hopper into which the raw material powder is charged, and a weighing unit that weighs the raw material powder from the hopper into different volumes with respect to time, and the weighing unit is configured to be formed. The above problem is solved by making the shape correlated with the film volume along the film trajectory.

According to the present invention, since the metering part has a shape that correlates with the film volume along the film formation locus, the supply amount of the raw material powder fluctuates according to fluctuations in the relative movement speed of the nozzle. As a result, it is possible to suppress the formation of a sparse film since the end slope is suppressed from becoming steep at the film formation start point of the first layer.

FIG. 3 is a cross-sectional view showing a cylinder head forming valve seat membranes using the cold spray device according to the present invention; FIG. 2 is an enlarged cross-sectional view of the periphery of the valve in FIG. 1; 1 is a configuration diagram showing an embodiment of a cold spray device according to the present invention; FIG. It is a front view showing a spray gun of one embodiment of a cold spray device according to the present invention. FIG. 5 is a cross-sectional view taken along line V-V of FIG. 4; FIG. 5 is a front view showing a state in which the spray gun of FIG. 4 is offset; It is a front view which shows the film-forming factory containing the cold spray apparatus which concerns on this invention. FIG. 8 is a plan view of FIG. 7; It is process drawing which shows the procedure which manufactures a cylinder head using the cold spray apparatus which concerns on this invention. 1 is a perspective view of a crude cylinder head material on which a valve seat membrane is formed using the cold spray apparatus according to the present invention; FIG. FIG. 11 is a cross-sectional view showing an intake port taken along line XI-XI of FIG. 10; FIG. 12 is a cross-sectional view showing a state in which an annular valve seat portion is formed in the intake port of FIG. 11 by a cutting process; FIG. 13 is a cross-sectional view showing a state in which a valve seat membrane is formed on the intake port of FIG. 12; FIG. 4 is a cross-sectional view showing an intake port with a valve seat membrane formed thereon; FIG. 10 is a cross-sectional view showing the intake port after the finishing process of FIG. 9; FIG. 4 is a cross-sectional view showing a raw material powder supply unit of FIG. 3; FIG. 17 is a perspective view showing the weighing unit of FIG. 16; FIG. 18 is a cross-sectional view along line XVIII-XVIII of FIG. 17; FIG. 4 is a plan view of a cylinder head rough material showing an example of a movement locus when the nozzle of the cold spray device moves over the openings of the intake port and the exhaust port in the film forming method according to the present invention. FIG. 20 is a plan view showing a movement trajectory for one intake port of FIG. 19; FIG. 21 is a plan view showing the shape of a weighing unit (disk) corresponding to the movement locus of FIG. 20; FIG. 22 is a developed cross-sectional view along line XXII-XXII of FIG. 21;

An embodiment of the present invention will be described below with reference to the drawings. First, an internal combustion engine 1 having a valve seat membrane, which is preferably applied to the film forming method and the cold spray apparatus of the present embodiment, will be described. FIG. 1 is a cross-sectional view of the internal combustion engine 1, and mainly shows the configuration around the cylinder head.

The internal combustion engine 1 includes a cylinder block 11 and a cylinder head 12 mounted on the upper portion of the cylinder block 11 . The internal combustion engine 1 is, for example, an in-line four-cylinder gasoline engine, and a cylinder block 11 has four cylinders 11a arranged in the depth direction of the drawing. Each cylinder 11a accommodates a piston 13 that reciprocates vertically in the figure, and each piston 13 is connected to a crankshaft 14 extending in the depth direction of the figure via a connecting rod 13a.

A mounting surface 12a of the cylinder head 12 to the cylinder block 11 has four recesses 12b forming combustion chambers 15 of the cylinders 11a at positions corresponding to the cylinders 11a. The combustion chamber 15 is a space for burning a mixture of fuel and intake air, and is composed of a recess 12b of the cylinder head 12, a top surface 13b of the piston 13, and an inner peripheral surface of the cylinder 11a.

The cylinder head 12 includes an intake port 16 that communicates the combustion chamber 15 and one side surface 12 c of the cylinder head 12 . The intake port 16 has a bent, substantially cylindrical shape and guides intake air into the combustion chamber 15 from an intake manifold (not shown) connected to the side surface 12c. The cylinder head 12 also includes an exhaust port 17 that communicates the combustion chamber 15 with the other side surface 12 d of the cylinder head 12 . The exhaust port 17 has a substantially cylindrical bent shape similar to the intake port 16, and discharges the exhaust generated in the combustion chamber 15 to an exhaust manifold (not shown) connected to the side surface 12d. Note that the internal combustion engine 1 of this embodiment includes two intake ports 16 and two exhaust ports 17 for each cylinder 11a.

The cylinder head 12 includes an intake valve 18 that opens and closes the intake port 16 with respect to the combustion chamber 15 and an exhaust valve 19 that opens and closes the exhaust port 17 with respect to the combustion chamber 15 . Each of the intake valve 18 and the exhaust valve 19 includes round bar-shaped valve stems 18a, 19a and disk-shaped valve heads 18b, 19b provided at the tips of the valve stems 18a, 19a. The valve stems 18 a and 19 a are slidably inserted through substantially cylindrical valve guides 18 c and 19 c assembled to the cylinder head 12 . As a result, each of the intake valve 18 and the exhaust valve 19 becomes movable relative to the combustion chamber 15 along the axial direction of the valve stems 18a and 19a.

FIG. 2 shows an enlarged view of the communicating portion between the combustion chamber 15 and the intake port 16 and the exhaust port 17 . The intake port 16 has a substantially circular opening 16 a in a portion communicating with the combustion chamber 15 . An annular valve seat membrane 16b that abuts on the valve head 18b of the intake valve 18 is formed on the annular edge of the opening 16a. When the intake valve 18 moves upward along the axial direction of the valve stem 18a, the upper surface of the valve head 18b contacts the valve seat membrane 16b to close the intake port 16. As shown in FIG. Conversely, when the intake valve 18 moves downward along the axial direction of the valve stem 18a, a gap is formed between the upper surface of the valve head 18b and the valve seat membrane 16b to open the intake port 16. As shown in FIG.

Like the intake port 16, the exhaust port 17 has a substantially circular opening 17a in a portion that communicates with the combustion chamber 15. The annular edge of the opening 17a is provided with an annular shape that contacts the valve head 19b of the exhaust valve 19. A valve seat membrane 17b is formed. When the exhaust valve 19 moves upward along the axial direction of the valve stem 19a, the upper surface of the valve head 19b comes into contact with the valve seat membrane 17b to close the exhaust port 17. As shown in FIG. Conversely, when the exhaust valve 19 moves downward along the axial direction of the valve stem 19a, a gap is formed between the upper surface of the valve head 19b and the valve seat membrane 17b to open the exhaust port 17. As shown in FIG. The diameter of the opening 16 a of the intake port 16 is set larger than the diameter of the opening 17 a of the exhaust port 17 .

In the 4-cycle internal combustion engine 1, only the intake valve 18 is opened when the piston 13 descends, thereby introducing the air-fuel mixture from the intake port 16 into the cylinder 11a (intake stroke). Subsequently, the intake valve 18 and the exhaust valve 19 are closed, and the piston 13 is raised to substantially the top dead center to compress the air-fuel mixture in the cylinder 11a (compression stroke). Then, when the piston 13 reaches substantially the top dead center, the compressed air-fuel mixture is ignited by the ignition plug and the air-fuel mixture explodes. Due to this explosion, the piston 13 descends to the bottom dead center, and the explosion is converted into rotational force via the connected crankshaft 14 (combustion/expansion stroke). Finally, when the piston 13 reaches the bottom dead center and starts rising again, only the exhaust valve 19 is opened to discharge the exhaust in the cylinder 11a to the exhaust port 17 (exhaust stroke). The internal combustion engine 1 generates an output by repeating the above cycle.

The valve seat membranes 16b, 17b are formed directly on the annular edges of the openings 16a, 17a of the cylinder head 12 by the cold spray method. In the cold spray method, a working gas having a temperature lower than the melting point or softening point of the raw material powder is made into a supersonic flow. The raw material powder is made to collide with the base material as it is, and the film is formed by plastic deformation of the raw material powder. Compared to the thermal spraying method, in which the material is melted and adhered to the base material, the cold spray method produces a dense film that is not oxidized in the atmosphere. It has characteristics such as high film speed, ability to form thick films, and high adhesion efficiency. In particular, it is suitable for use as a structural material such as the valve seat membranes 16b and 17b of the internal combustion engine 1 because the film formation speed is high and a thick film can be formed.

FIG. 3 is a diagram schematically showing the cold spray device 2 of this embodiment used for forming the valve seat membranes 16b and 17b. The cold spray apparatus 2 of this embodiment includes a gas supply unit 21 that supplies a working gas and a carrier gas, a raw material powder supply unit 22 that supplies raw material powder for the valve seat membranes 16b and 17b, and a raw material powder that is heated below its melting point. A spray gun 23 that sprays a supersonic flow using a working gas, and a coolant circulation circuit 27 that cools the nozzle 23d are provided.

The gas supply unit 21 includes a compressed gas cylinder 21a, a working gas line 21b and a carrier gas line 21c. The working gas line 21b and the carrier gas line 21c are each provided with a pressure regulator 21d, a flow control valve 21e, a flow meter 21f and a pressure gauge 21g. A pressure regulator 21d, a flow control valve 21e, a flow meter 21f, and a pressure gauge 21g are used to regulate the pressure and flow rate of the working gas and carrier gas from the compressed gas cylinder 21a.

A heater 21i such as a tape heater is installed in the working gas line 21b, and the heater 21i heats the working gas line 21b by being supplied with power from a power source 21h through power supply lines 21j, 21j. . The working gas is introduced into the chamber 23a of the spray gun 23 after being heated to a temperature lower than the melting point or softening point of the raw material powder by the heater 21i. A pressure gauge 23b and a thermometer 23c are installed in the chamber 23a, and the pressure value and temperature value detected via respective signal lines 23g, 23g are output to a controller (not shown) for feedback control of pressure and temperature. served to

On the other hand, the raw material powder supply unit 22 includes a raw material powder supply device 22a, a weighing unit 22b attached thereto, and a raw material powder supply line 22c. The carrier gas from the compressed gas cylinder 21a passes through the carrier gas line 21c and is introduced into the raw material powder supply device 22a. A predetermined amount of raw material powder weighed by the weighing unit 22b is conveyed into the chamber 23a through the raw material powder supply line 22c.

The spray gun 23 sprays the raw material powder P conveyed into the chamber 23a by the carrier gas as a supersonic flow by the working gas from the tip of the nozzle 23d, and causes it to collide with the substrate 24 in a solid phase state or a solid-liquid coexistence state. to form a film 24a. In this embodiment, the cylinder head 12 is used as the base material 24, and the valve seat membranes 16b, 17b are formed by spraying the raw material powder P onto the annular edges of the openings 16a, 17a of the cylinder head 12 by the cold spray method. to form

The nozzle 23d has a channel (not shown) through which a coolant such as water flows. The nozzle 23d has a coolant introduction portion 23e at its tip that introduces coolant into the flow path, and a coolant discharge portion 23f that discharges the coolant in the flow path at its base end. The nozzle 23d cools the nozzle 23d by introducing the coolant into the channel from the coolant introduction part 23e, flowing the coolant in the channel, and discharging the coolant from the coolant discharge part 23f.

A refrigerant circulation circuit 27 that circulates the refrigerant in the flow path of the nozzle 23d includes a tank 271 that stores the refrigerant, an introduction pipe 274 connected to the above-described refrigerant introduction portion 23e, and an introduction pipe 274 that connects the tank 271 and the nozzle. 23d, a cooler 273 for cooling the coolant, and a discharge pipe 275 connected to the coolant discharge portion 23f. The cooler 273 is composed of, for example, a heat exchanger or the like, and cools the refrigerant by exchanging heat between the refrigerant whose temperature is increased by cooling the nozzle 23d and the refrigerant such as air, water, or gas.

The refrigerant circulation circuit 27 sucks the refrigerant stored in the tank 271 by the pump 272 and supplies the refrigerant to the refrigerant introduction portion 23 e via the cooler 273 . The coolant supplied to the coolant introduction portion 23e flows through the flow path in the nozzle 23d from the front end side toward the rear end side, and during this time, it exchanges heat with the nozzle 23d to cool the nozzle 23d. The coolant that has flowed to the rear end side of the flow path is discharged from the coolant discharge portion 23 f to the discharge pipe 275 and returns to the tank 271 . In this manner, the refrigerant circulation circuit 27 cools the nozzle 23d by circulating the refrigerant while cooling it, so that the adhesion of the raw material powder P to the injection passage of the nozzle 23d can be suppressed.

The valve seats of the cylinder head 12 are required to have high heat resistance and wear resistance to withstand impact input from valves in the combustion chamber 15 and high thermal conductivity for cooling the combustion chamber 15 . In response to these requirements, valve seat membranes 16b and 17b made of precipitation-hardened copper alloy powder, for example, are harder than the cylinder head 12 made of casting aluminum alloy, and have high heat resistance and wear resistance. Excellent valve seats can be obtained.

In addition, since the valve seat membranes 16b and 17b are formed directly on the cylinder head 12, a higher thermal conductivity can be obtained compared to conventional valve seats formed by press-fitting separate seat rings into the port openings. can be done. Furthermore, compared to using a seat ring as a separate part, it is possible to make it closer to the cooling water jacket. Secondary effects such as promotion of tumble flow can also be obtained.

As the raw material powder P used for forming the valve seat membranes 16b and 17b, it is preferable to use a metal that is harder than the aluminum alloy for casting and that provides the heat resistance, abrasion resistance, and thermal conductivity required for the valve seat. For example, it is preferable to use the precipitation hardening copper alloy described above. As the precipitation hardening copper alloy, a Corson alloy containing nickel and silicon, a chromium copper containing chromium, a zirconium copper containing zirconium, or the like may be used. Further, for example, precipitation hardenable copper alloys containing nickel, silicon and chromium, precipitation hardenable copper alloys containing nickel, silicon and zirconium, precipitation hardenable alloys containing nickel, silicon, chromium and zirconium, precipitations containing chromium and zirconium. A hardening type copper alloy or the like can also be applied.

Moreover, the valve seat membranes 16b and 17b may be formed by mixing a plurality of kinds of raw material powders, for example, a first raw material powder and a second raw material powder. In this case, for the first raw material powder, it is preferable to use a metal that is harder than the casting aluminum alloy and that provides the heat resistance, wear resistance, and thermal conductivity required for the valve seat. Precipitation hardening copper alloys are preferably used. Moreover, as the second raw material powder, it is preferable to use a metal harder than the first raw material powder. Alloys such as iron-based alloys, cobalt-based alloys, chromium-based alloys, nickel-based alloys, and molybdenum-based alloys, and ceramics may be applied to the second raw material powder. Also, one of these metals may be used alone, or two or more thereof may be used in appropriate combination.

The valve seat membrane formed by mixing the first raw material powder and the second raw material powder harder than the first raw material powder has better heat resistance than the valve seat membrane formed only from the precipitation hardening copper alloy. durability and wear resistance can be obtained. Such an effect is obtained because the second raw material powder removes the oxide film existing on the surface of the cylinder head 12 to expose and form a new interface, thereby improving the adhesion between the cylinder head 12 and the metal film. It is considered to be for Further, it is also considered that the adhesion between the cylinder head 12 and the metal coating is improved due to the anchoring effect of the second raw material powder sinking into the cylinder head 12 . Furthermore, when the first raw material powder collides with the second raw material powder, part of the kinetic energy is converted into heat energy, or generated in the process of plastic deformation of part of the first raw material powder. It is also considered that the heat accelerates precipitation hardening in a part of the precipitation hardening copper alloy used as the first raw material powder.

In the cold spray device 2 of this embodiment, the cylinder head 12 on which the valve seat membranes 16b and 17b are formed is fixed to the base 45, while the tip of the nozzle 23d of the spray gun 23 is attached to the openings 16a and 16b of the cylinder head 12. The raw material powder is jetted by rotating along the annular edge of 17a. Since the cylinder head 12 is not rotated, it does not require a large occupied space, and since the inertia moment of the spray gun 23 is smaller than that of the cylinder head 12, it is excellent in rotational transient characteristics and responsiveness. However, as shown in FIG. 3, the spray gun 23 is connected to a high-pressure pipe (high-pressure hose) that constitutes the working gas line 21b. Deformation stiffness due to torsion may impede rotational transient characteristics and responsiveness. Therefore, the cold spray device 2 of the present embodiment is configured as shown in FIGS. 4 to 8 to enhance the transient characteristics and responsiveness of rotation.

4 is a front view showing a spray gun 23 of one embodiment of the cold spray device 2 according to the present invention, FIG. 5 is a cross-sectional view along line VI-VI in FIG. 4, and FIG. FIG. 7 is a front view showing a state in which the gun 23 is offset, FIG. 7 is a front view showing a film forming factory including the cold spray device 2 according to the present invention, and FIG. 8 is a plan view of FIG.

The cylinder head 12, which is a workpiece, is mounted in a predetermined posture on a base 45 of a film forming booth 42 of the film forming factory 4 shown in FIGS. For example, as shown in FIG. 10, the cylinder head 12 is fixed to the base 45 so that the concave portion 12b of the cylinder head 12 faces upward, and the center line of the opening 16a of the intake port 16 or the opening 17a of the exhaust port 17 is measured. The base 45 is tilted so that the center line of is in the vertical direction.

The film forming factory 4 includes a film forming booth 42 for performing film forming processing and a transport booth 41. The film forming booth 42 holds a base 45 on which the cylinder head 12 is mounted and a spray gun 23. An industrial robot 25 is installed. A transport booth 41 is provided in front of the film forming booth 42 , and the cylinder head 12 is carried in and out from the outside through a door 43 . is performed by the door 44. For example, while film-forming processing is being performed on one cylinder head 12 in the film-forming booth 42 , the cylinder head 12 that has completed the processing before that is carried out from the transport booth 41 to the outside. Since the film formation process by the cold spray device 2 generates noise due to the shock waves of the supersonic flow and the raw material powder scatters, the transport booth 41 is installed and the door 44 is closed to perform the film formation process. Other operations such as unloading of the cylinder head 12 after processing and loading of the cylinder head 12 before processing can be performed at the same time as the film formation processing.

The spray gun 23 is rotatably mounted on a base plate 26 fixed to a hand 251 of an industrial robot 25 installed in the film forming booth 42 of the film forming factory 4 shown in FIGS. The configuration of the spray gun 23 of this embodiment will be described below with reference to FIGS. 4 to 6. FIG. First, as shown in FIG. 4, a bracket 252 is fixed to a hand 251 of an industrial robot 25, a base plate 26 is rotatably attached to the bracket 252, and a spray gun 23 is fixed to the base plate 26. .

More specifically, as shown in FIGS. 4 and 5, a bracket 252 is fixed to the hand 251 of the industrial robot 25, the main body of the motor 29 is fixed to this bracket 252, and the drive shaft 291 of the motor 29 is It is connected to the first base plate 261 via pulleys and belts (not shown) to rotate the first base plate 261 with respect to the bracket. The motor 29 reciprocates, for example, in a maximum range of 360°. For example, when the raw material powder is injected by rotating the driving shaft 291 clockwise 360 degrees with respect to the opening 16a of one intake port 16, the driving shaft 291 is rotated counterclockwise 360 degrees to return to the original position. Then, the raw material powder is injected into the next opening 16a of the intake port 16 by rotating the drive shaft 291 clockwise by 360°, and this is repeated thereafter.

The base plate 26 consists of a first base plate 261 and a second base plate 262. These first base plate 261 and second base plate 262 slide in a direction perpendicular to the rotation axis C (horizontal direction in FIG. 4) via a linear guide 281. provided as possible. By driving the fluid pressure cylinder 282, the offset amount of the second base plate 262 with respect to the first base plate 261 is adjusted, and the injection diameter D of the film forming material is set.

A cover 263 is attached to the second base plate 262, and the spray gun 23 is fixed to its lower end. The spray gun 23 is fixed to the second base plate 262 via the cover 263 so that the spray direction of the nozzle 23d faces the rotation axis C. As shown in FIG. However, since the second base plate 262 can be offset with respect to the first base plate 261 by the linear guide 281 and the fluid pressure cylinder 282 described above, the position of the tip of the nozzle 23d of the spray gun 23 can be adjusted with respect to the rotation axis C. can be adjusted horizontally.

In this way, when the position of the tip of the nozzle 23d is set on the line of the rotation axis C shown in FIG. 4 to a position away from the rotation axis C as shown in FIG. The diameter D becomes smaller. Since the opening 16a of the intake port 16 has a larger diameter than the opening 17a of the exhaust port 17, when forming the valve seat membrane 16b in the opening 16a of the intake port 16, the rotation axis C shown in FIG. When the valve seat membrane 17b is formed in the opening 17a of the exhaust port 17, it may be positioned away from the rotation axis C shown in FIG.

A working gas line 21b for guiding a high-pressure gas of 3 to 10 MPa supplied from a compressed gas cylinder 21a shown in FIG. It hangs down from the top of the base plate 26 attached to the hand 251 of the industrial robot 25 and reaches the spray gun 23 . In the vicinity of the base plate 26 therebetween, as shown in FIG. 4, they are separated and connected via a rotary joint 21k such as a swivel joint, and a heater 21i is provided below it. The working gas line 21b extending from the rotary joint 21k to the chamber 23a shown in FIG. are routed to The working gas line 21b may be formed, for example, in a helical shape in advance so as to surround the rotation axis C. A shape-retaining mold may be provided on the outer circumference so that the hose follows the spiral shape.

A raw material powder supply line 22c for guiding the raw material powder supplied from the raw material powder supply device 22a shown in FIG. It hangs down from the top and reaches the spray gun 23 . Below the base plate 26 therebetween, the raw material powder supply line 22c is composed of a pipe including a metal pipe and a metal joint, and is connected to the chamber 23a of the spray gun 23, as shown in FIG.

Power supply lines 21j, 21j for guiding the power supplied from the power source 21h shown in FIG. 3 to the heater 21i are routed around the industrial robot 25 as the tube bundle 20 shown in FIG. , is connected to the heater 21i. A signal line 23g for outputting a detection signal from the pressure gauge 23b shown in FIG. from the chamber 23a of the spray gun 23 in a state of being inserted through a pipe including a metal pipe and a metal joint, and is guided from the chamber 23a of the spray gun 23 to the second base plate 262, and another working gas line 21b, a raw material powder supply line 22c, an electric power It is wired around the industrial robot 25 from the top of the base plate 26 together with the supply line 21j.

An introduction pipe 274 and a discharge pipe 275 for guiding the refrigerant supplied from the refrigerant circulation circuit 27 shown in FIG. It hangs down from the top of the base plate 26 and is connected to a coolant introduction portion 23e at the tip of the nozzle 23d and a coolant discharge portion 23f at the base end of the nozzle 23d. Below the base plate 26 therebetween, the introduction pipe 274 and the discharge pipe 275 are composed of pipes including metal pipes and metal joints, and are connected to the nozzle 23d of the spray gun 23, as shown in FIG.

As described above, the working gas line 21b composed of a high-pressure hose that is hard and has high deformation rigidity has its rotary joint 21k arranged on the line of the rotation axis C as shown in FIG. It is routed along the axis of rotation C to surround it. Besides the working gas line 21b, the power supply lines 21j, 21j, the raw material powder supply line 22c, the refrigerant introduction pipe 274 and discharge pipe 275, and the signal lines 23g, 23h are connected to the rotation axis C as shown in FIG. It is arranged at a position surrounding the working gas line 21b.

Next, a method of manufacturing the cylinder head 12 having the valve seat membranes 16b, 17b will be described. FIG. 9 is a process diagram showing the process of processing the valve portion in the method of manufacturing the cylinder head 12 of this embodiment. As shown in the figure, the method for manufacturing the cylinder head 12 of this embodiment includes a casting step S1, a cutting step S2, a coating step S3, and a finishing step S4. Processing steps other than the valve portion are omitted for simplification of explanation.

In the casting step S1, an aluminum alloy for casting is poured into a mold in which a sand core is set, and a crude cylinder head material having intake ports 16, exhaust ports 17, etc. formed in the main body is cast. The intake port 16 and the exhaust port 17 are formed with a sand core, and the recess 12b is formed with a mold. FIG. 10 is a perspective view of the cylinder head rough material 3 cast and formed in the casting step S1, viewed from the side of the mounting surface 12a to the cylinder block 11. As shown in FIG. The cylinder head rough material 3 includes four recesses 12b and two intake ports 16 and two exhaust ports 17 provided in each recess 12b. The two intake ports 16 and the two exhaust ports 17 of each concave portion 12b are brought together in the cylinder head rough material 3 and communicate with openings provided on both side surfaces of the cylinder head rough material 3, respectively.

FIG. 11 is a cross-sectional view of the cylinder head blank 3 taken along line XI-XI in FIG. 10, showing the intake port 16. FIG. The intake port 16 is provided with a circular opening 16a exposed in the recess 12b of the cylinder head rough material 3. As shown in FIG.

In the next cutting step S2, the cylinder head rough material 3 is milled by an end mill, a ball end mill, or the like to form an annular valve seat portion 16c in the opening 16a of the intake port 16, as shown in FIG. The annular valve seat portion 16c is an annular groove that forms the base shape of the valve seat membrane 16b and is formed on the outer periphery of the opening 16a. In the method of manufacturing the cylinder head 12 of the present embodiment, the raw material powder P is sprayed onto the annular valve seat portion 16c by a cold spray method to form a film, and the valve seat film 16b is formed based on this film. Therefore, the annular valve seat portion 16c is formed in a size one size larger than the valve seat membrane 16b.

In the covering step S3, the raw material powder P is sprayed onto the annular valve seat portion 16c of the crude cylinder head material 3 using the cold spray device 2 of the present embodiment to form the valve seat film 16b. More specifically, in this covering step S3, as shown in FIG. 13, the raw material powder P is placed on the annular valve seat while maintaining the annular valve seat portion 16c and the nozzle 23d of the spray gun 23 in the same posture and at a constant distance. The spray gun 23 is rotated at a constant speed while the cylinder head rough material 3 is fixed so that the entire circumference of the portion 16c can be sprayed.

The tip of the nozzle 23 d of the spray gun 23 is held by the hand 251 of the industrial robot 25 above the cylinder head 12 fixed to the base 45 . The base 45 or the industrial robot 25 is mounted on the cylinder head 12 or the spray so that the center axis Z of the intake port 16 on which the valve seat membrane 16b is formed is vertical and overlaps the rotation axis C, as shown in FIG. The position of the gun 23 is set. In this state, the spray gun 23 is rotated around the C-axis by the motor 29 while the raw material powder P is sprayed from the nozzle 23d onto the annular valve seat portion 16c, thereby forming a coating on the entire circumference of the annular valve seat portion 16c.

While the coating step S3 is being performed, the nozzle 23d introduces the coolant supplied from the coolant circulation circuit 27 into the flow channel through the coolant introduction portion 23e. The coolant cools the nozzle 23d while flowing from the front end side to the rear end side of the channel formed inside the nozzle 23d. The coolant that has flowed to the rear end side of the channel is discharged from the channel by the coolant discharge portion 23f and recovered.

When the spray gun 23 makes one rotation about the C axis and the formation of the valve seat membrane 16b is completed, the rotation of the spray gun 23 is temporarily stopped. During this stoppage of rotation, the industrial robot 25 moves the spray gun 23 so that the center axis Z of the intake port 16 where the valve seat membrane 16b is formed next coincides with the reference axis of the industrial robot 25 . After the industrial robot 25 finishes moving the spray gun 23 , the motor 29 restarts the rotation of the spray gun 23 to form the valve seat membrane 16 b in the next intake port 16 . Thereafter, by repeating this operation, the valve seat membranes 16b, 17b are formed on all the intake ports 16 and the exhaust ports 17 of the crude cylinder head material 3. As shown in FIG. When the target for forming the valve seat film is switched between the intake port 16 and the exhaust port 17 , the base 45 changes the inclination of the cylinder head rough material 3 .

Now, FIG. 19 shows an example of a movement trajectory MT when the nozzle 23d of the cold spray device 2 moves through the openings of the intake port 16 and the exhaust port 17 in the film formation method according to the present invention. 3 is a plan view of FIG. The nozzle 23d is moved relative to the openings 16a of the eight intake ports 16 and the openings 17a of the eight exhaust ports 17 of the cylinder head rough material 3 shown in FIG. Although the movement locus MT with respect to the intake port 16 will be described below, the movement locus MT with respect to the exhaust port 17 is also set in the same manner.

As described above, when the nozzle 23d rotates 360° clockwise with respect to one intake port 16, it rotates 360° counterclockwise before moving to the next intake port 16, returns to its original position, and then also rotate clockwise 360° with respect to the intake port 16 of . The nozzle 23d injects the raw material powder into each of the eight intake ports 16 while rotating clockwise by 360°. This circular trajectory is called a deposition trajectory T. FIG. The illustrated film formation locus T is a locus of 360° clockwise, but may be a locus of 360° counterclockwise.

Here, the movement trajectory MT for the eight intake ports 16 includes a circular film formation trajectory T for each of the annular valve seat portions 16c of each intake port 16, and a connection trajectory CT connecting the adjacent circular film formation trajectories T. and is a series of continuous trajectories. Then, the nozzle 23d is moved along the movement trajectory MT while continuously injecting the raw material powder from the nozzle 23d without interruption. The circular film formation trajectory T for one annular valve seat portion 16c starts from the film formation start point, moves clockwise or counterclockwise, wraps at the film formation start point, and wraps around the film formation end point. and

FIG. 20 is an enlarged plan view showing the movement locus MT for the openings 16a1 to 16a8 of one intake port 16 in FIG. Since the nozzle 23d is rotated clockwise with respect to the annular valve seat portion 16c of the opening 16a of the intake port 16, the movement trajectory MT shown in FIG. is linearly moved to the annular valve seat portion 16c (P1, connection locus CT), and the nozzle 23d is rotated clockwise along the circular film formation locus T with this as the film formation start point P2 (P3 to P5). 20, the nozzle 23d is moved rightward in FIG. 20 (P1, connection locus CT). In such a movement trajectory MT, a first turning point at which the movement speed of the nozzle 23d becomes zero occurs at the film formation start point P2 of the annular valve seat portion 16c, and the movement speed of the nozzle 23d decreases at the film formation end point P6. A second turning point to zero occurs. Note that the turning point is a point on the movement trajectory MT at which the movement speed of the nozzle 23d becomes zero, and is a point at which the movement trajectory changes to a right angle or an acute angle (≦90°).

At the first turnaround point occurring at the film formation start point P2, the velocity of the nozzle 23d temporarily becomes zero, but since the injection of the raw material powder is continued, the end portion of the valve seat film 16b forming the first layer. slope becomes steeper. In the cold spray method, the raw material powder in a solid state is collided with the base material at supersonic speed to plastically deform it. The raw material powder for the second layer is not sufficiently flattened, and the pore diameter within the layer of the valve seat membrane for the second layer increases. This type of problem of increased porosity due to insufficient flatness is attributed to the fact that the edge portion of the valve seat membrane constituting the first layer becomes steep. In other words, of the circular film formation trajectory T of the annular valve seat portion 16c, which is the film formation target portion, the range from the film formation start point P2 to the film formation end point P6 (including end points) is the turning point at the first layer. is included, the edge slope becomes steep at that point. However, even if the trajectory of film formation for the second layer in the wrap portion includes a turning point, the problem of insufficient flatness does not occur as long as the end slope of the valve seat film for the first layer is not steep.

Therefore, in the film forming method of the present embodiment, when the turning point is included in the first layer of the circular film forming trajectory T, the raw material powder for a predetermined range of the film forming trajectory T including at least the turning point of the first layer is set to be smaller than the supply amount of the raw material powder for the range of the other film formation trajectories T. In addition to this, when the second layer includes a turning point, from the viewpoint of suppressing the surplus film, the supply amount of the raw material powder for a predetermined range of the film formation trajectory T including the turning point of the second layer is is set to be smaller than the supply amount of the raw material powder for the range of the film formation locus T of . In addition to this, from the viewpoint of suppressing surplus coating, the supply amount of the raw material powder to the connection trajectory CT connecting one film formation trajectory T and the film formation trajectory T adjacent thereto is changed to another film formation trajectory. It is set to be less than the supply amount of raw material powder for the range of T.

That is, in the cold spray device 2 of the present embodiment and the film formation method using the same, the predetermined range including the film formation start point P2 and the film formation end point P6 of the annular valve seat portion 16c is larger than the other ranges. The supply amount of the raw material powder is set to be small, and more preferably, in the range where the films overlap at the film formation start point P2 and the film formation end point P6, the thickness of the overlapping film is made equal to the thickness of the film in the other ranges. The supply amount of the raw material powder shall be such that Also, the range from the point P1 to the film formation start point P2, which is the connection locus CT, and the range from the film formation end point P6 to the next film formation start point P2 are set so that the supply amount of the raw material powder is minimized.

16 to 22 are diagrams showing the specific configuration of the raw material powder supply section 22 for controlling the supply amount of the raw material powder as described above, and FIG. 16 is a cross section showing the raw material powder supply section 22 of FIG. 17 is a perspective view showing the weighing portion 22b of FIG. 16, and FIG. 18 is a cross-sectional view taken along line XVIII--XVIII of FIG.

As shown in FIG. 16, the raw material powder supply unit 22 includes a hopper 221 into which the raw material powder is introduced, and a weighing unit 22b that measures the raw material powder from the hopper 221 into different volumes over time. The weighing unit 22b includes a disc 222, a driving unit 226 that rotates the disc 222 at a constant rotational speed when the raw material powder is supplied, and an annular groove 223 that is formed on the upper surface of the disc 222 and receives the raw material powder from the hopper 221. , provided. Raw material powder is put into the hopper 221 from the top, and the raw material powder is received by the annular groove 223 of the disc 222 of the weighing unit 22b by its own weight.

17 and 18, when the disk 222 rotates, the upper edge of the opening of the annular groove 223 is leveled horizontally at the position where the raw material powder is supplied from the hopper 221 by its own weight. A first scraper 224 is provided to scrape away the powder. Also, when the disk 222 rotates, the upper edge of the opening of the annular groove 223 is leveled horizontally at the position where the raw material powder received in the annular groove 223 of the disk 222 is sucked into the raw material powder supply line 22c. A second scraping member 225 is provided for scraping off the raw material powder. The first scraping member 224 and the second scraping member 225 more accurately measure the supply amount of the raw material powder measured by the annular groove 223 and supply it to the spray gun 23 via the raw material powder supply line 22c.

The rotation of the disk 222 and the relative movement of the nozzle 23d are synchronized by a controller (not shown) of the cold spray device 2. FIG. For example, one unit of movement trajectory MT of nozzle 23d corresponds to one rotation of disk 222, and disk 222 rotates at a constant speed in synchronization with movement of nozzle 23d along one unit of movement trajectory MT. do. Here, one unit of the movement trajectory MT of the nozzle 23d is a repetition unit in which the film forming process for the eight intake ports 16 shown in FIG. 19 is completed by repeating this. The disk 222 rotates once in synchronism with the movement of the nozzle 23d along the movement locus MT of one unit. become.

That is, as shown in FIG. 17, the annular groove portion 223 of the disc 222 has the same width over the entire circumference, but the depth of the bottom surface of the annular groove portion 223 is equal to the film formation locus T of the annular valve seat portion 16c. The depth corresponds to one unit of . For example, assuming that the connection locus CT and the film formation locus T for one annular valve seat portion 16c correspond to one rotation of the disk 222, the bottom depth of one round of the annular groove portion 223 is shown in FIG. is formed as 21 is a plan view showing the shape of the weighing portion 22b (disk) corresponding to the movement locus MT of FIG. 20, and FIG. 22 is a developed cross-sectional view along line XXII--XXII of FIG.

The positions of the annular groove portion 223 of the disk 222 indicated by symbols P2 and P6 in FIG. 21 correspond to the film formation start point P2 and the film formation end point P6 of the movement locus MT in FIG. and P5 correspond to positions P3, P4 and P5 of the movement trajectory MT in FIG. When the nozzle 23d is moved from P1 of the connection locus CT toward the film formation start point P2, the movement speed of the nozzle 23d approaches 0 as the film formation start point P2 is approached, and becomes 0 at the film formation start point P2. Thereafter, the nozzle 23d gradually increases its speed, reaches a predetermined speed at position P2', and moves from there to position P6s' while maintaining the predetermined speed. Finally, the movement speed of the nozzle 23d approaches 0 as the film formation end point P6 is approached, and after reaching 0 at the film formation end point P6, the speed is gradually increased toward the next adjacent annular valve seat portion 16c.

When the nozzle 23d is moved along the movement locus MT in this manner, the movement speed differs depending on the position, so the film thickness becomes relatively thick in the range where the movement speed is slow. Specifically, since the moving speed of the nozzle 23d in the range from the film formation start point P2 to the position P2' and the range from the position P6' to the film formation end point P6 shown in FIG. 21 is relatively slow, the film thickness becomes relatively thick. Therefore, as shown in the developed cross-sectional view of FIG. 22, the depth D1 of the bottom surface of the annular groove portion 223 in the range from position P2' to position P6' in the clockwise direction is assumed to be a constant depth, while the film formation start point P2 Also, the depth D2 of the bottom surface of the annular groove portion 223 at the film formation end point P6 is set to a value shallower than the depth D1. Further, the depth of the bottom surface of the annular groove portion 223 in the range from the film formation start point P2 to the position P2' is gradually inclined to the depth D1 from the bottom surface (depth D2) of the annular groove portion 223 at the film formation start point P2. Similarly, the depth of the bottom surface of the annular groove portion 223 in the range from the film formation end point P6 to the position P6' in the counterclockwise direction gradually increases from the bottom surface (depth D2) of the annular groove portion 223 at the film formation end point P6. , the depth of the slope is set to be the depth D1.

Preferably, the supply amount of raw material powder is determined by the volume of the annular groove portion 223 in the range from the film formation start point P2 to the position P2′, and the volume of the annular groove portion 223 in the range from the film formation end point P6 to the position P6′. The total amount of raw material powder supplied, that is, the amount of raw material powder supplied to the lap portion of the film, is equal to the amount of raw material powder supplied to the range from position P2' to position P6' corresponding to the same distance. As a result, the film thickness of the film on the lap portion and the film thickness of the film on the other portions become equal, thereby facilitating the process of removing the surplus film.

Incidentally, when the nozzle 23d is relatively moved along the connection trajectory CT connecting the film formation trajectories T among the movement trajectories MT, the supply amount of the raw material powder is minimized as indicated by the position P1 in FIG. It is desirable to set the depth D3 of the bottom surface of the annular groove 223 to the shallowest. By doing so, the film thickness of the surplus film formed on the mounting surface 12a of the cylinder head rough material 3 is reduced, so that the removal depth of the surplus film in the finishing step S4 can be made shallow.

Returning to FIG. 9, in the finishing step S4, the valve seat membranes 16b and 17b, the intake port 16 and the exhaust port 17 are finished. In the finishing of the valve seat membranes 16b and 17b, the surfaces of the valve seat membranes 16b and 17b are cut by milling using a ball end mill to prepare the valve seat membrane 16b into a predetermined shape. Further, in finishing the intake port 16, a ball end mill is inserted into the intake port 16 from the opening 16a, and the inner peripheral surface of the intake port 16 on the opening 16a side is cut along the processing line PL shown in FIG. . The processing line PL is a range in which the surplus film SF to which the raw material powder P is scattered and adhered inside the intake port 16 is formed relatively thick. It is a range that is formed thick enough to affect the thickness.

In this manner, the finishing step S4 can eliminate surface roughness of the intake port 16 due to casting and remove the surplus film SF formed in the covering step S3. FIG. 15 shows the intake port 16 after the finishing step S4. As with the intake port 16, the exhaust port 17 is formed by forming a small diameter portion in the exhaust port 17 by casting, forming an annular valve seat portion by cutting, cold spraying the annular valve seat portion, and finishing. After that, the valve seat membrane 17b is formed. Therefore, a detailed description of the procedure for forming the valve seat membrane 17b for the exhaust port 17 will be omitted.

As described above, the film formation method using the cold spray device 2 of the present embodiment is to move the cylinder head rough material 3 having the annular valve seat portion 16c and the nozzle 23d of the cold spray device 2 along the film formation trajectory T. in a film formation method in which a film is formed on the annular valve seat portion 16c while the raw material powder supplied from the raw material powder supply unit 22 is ejected from the nozzle 23d. and a weighing unit 22b for weighing the raw material powder from the hopper 221 into different volumes with respect to time. Correlated shapes. As a result, even if the second valve seat film 16b, which is the end point of film formation, is superimposed on the valve seat film 16b, the collision direction is substantially perpendicular to the surface of the first valve seat film 16b. The raw material powder for the second layer is sufficiently flattened, and the pore diameter within the layer of the valve seat membrane 16b is sufficiently small.

Further, in the film forming method using the cold spray apparatus 2 of the present embodiment, the weighing unit 22b is formed on the disk 222, the drive unit 226 that rotates the disk 222 at a constant rotational speed, and the upper surface of the disk 222. , and an annular groove portion 223 corresponding to one unit of the film formation locus T of the annular valve seat portion 16c and receiving the raw material powder from the hopper 221, so that the relative movement of the nozzle 23d and the rotation of the disk 222 are synchronized. In this case, the metering portion 22b assumes a shape correlated with the film volume along the film formation trajectory T simply by rotating the disk 222 at a predetermined speed.

In addition, in the film formation method using the cold spray apparatus 2 of the present embodiment, since the bottom surface of the annular groove 223 of the disk 222 has a depth that correlates with the film volume along the film formation locus T, simple In the configuration, the measuring portion 22b can have a shape that correlates with the film volume along the film formation trajectory T. FIG.

Further, in the film formation method using the cold spray apparatus 2 of the present embodiment, the relative movement trajectory MT between the cylinder head rough material 3 and the nozzle 23d is divided into one film formation trajectory T and another film formation trajectory T. , and the volume of the annular groove portion 223 corresponding to the connection locus CT is set smaller than the volume corresponding to the other film formation locus T. The film thickness of the surplus film formed becomes thin. As a result, the depth of removal of the surplus film in the finishing step S4 can be made shallow.

In addition, in the film formation method using the cold spray device 2 of the present embodiment, the weighing unit 22b horizontally smoothes the upper edge of the opening of the annular groove 223 to scrape off excess raw material powder. The amount of raw material powder to be supplied becomes more accurate.

Further, in the film formation method using the cold spray device 2 of the present embodiment, the workpiece is the engine cylinder head rough material 3, the film formation portion is the annular valve seat portion 16c, and the film formation trajectory T is the annular valve seat A circular trajectory having predetermined positions on the portion 16c as a film formation start point P2 and a film formation end point P6. ∼ P2′ and P6′ to P6 are set so that the volume of the measuring parts in the range corresponding to the predetermined distance in the range P2′ to P6′ where the films do not overlap is set as the target volume. Therefore, the thickness of the coating becomes uniform over the entire deposition locus T, and the depth of removal of the surplus coating in the finishing step S4 can be made shallow.

The annular valve seat portion 16c corresponds to the film-forming portion according to the present invention.

DESCRIPTION OF SYMBOLS 1... Internal combustion engine 11... Cylinder block 11a... Cylinder 12... Cylinder head 12a... Mounting surface 12b... Recess 12c, 12d... Side surface 13... Piston 13a... Connecting rod 13b... Top surface 14... Crankshaft 15... Combustion chamber 16... Intake port 16a... Opening 16b... Valve seat membrane 16c... Annular valve seat portion 17... Exhaust port 17a... Opening 17b... Valve seat membrane 18... Intake valve 18a... Valve stem 18b... Valve head 18c... Valve guide 19... Exhaust valve 19a... Valve stem 19b Valve head 19c Valve guide 2 Cold spray device 21 Gas supply unit 21a Compressed gas cylinder 21b Working gas line 21c Carrier gas line 21d Pressure regulator 21e Flow control valve 21f Flow meter 21g Pressure gauge 21h Power source 21i Heater 21j Power supply line 21k Rotary joint 22 Raw material powder supply unit 22a Raw material powder supply device 22b Weighing unit 22c Raw material powder supply line 221 Hopper 222 Disk 223 Annular groove 224 First scraped material 225 Second scraped material 226 Actuator 23 Spray gun 23a Chamber 23b Pressure gauge 23c Thermometer 23d Nozzle 23e Refrigerant introduction part 23f Refrigerant discharge part 23g Signal line 24 Substrate 24a Film 25 Industrial robot 251 Hand 252 Bracket 26 Base plate 261 First base plate 262 Second base plate 263 Cover 27 Refrigerant circulation circuit 271 Tank 272 Pump 273 Cooler 274 Introduction Pipe 275... Discharge pipe 28... Offset mechanism 281... Linear guide 282... Fluid pressure cylinder 29... Motor 291... Drive shaft 3... Cylinder head rough material 4... Film formation factory 41... Transport booth 42... Film formation booth 43, 44... Door 45... Base MT... Movement trajectory T... Trajectory of film-forming portion CT... Connection trajectory

Claims (6)

A workpiece having a film-forming portion and a nozzle of a cold spray device are relatively moved along a film-forming trajectory with respect to the film-forming portion, and raw material powder supplied from a raw material powder supply unit is sprayed from the nozzle. However, in the film forming method for forming a film on the film forming portion,
The raw material powder supply unit comprises a hopper into which the raw material powder is fed, and a weighing unit that weighs the raw material powder from the hopper into different volumes over time,
The measuring part has a shape correlated with the film volume along the film formation trajectory ,
wherein the workpiece is an engine cylinder head rough material, and the film-forming portion is an annular valve seat portion;
The film formation trajectory is a circular trajectory having a film formation start point and a film formation end point at predetermined positions on the annular valve seat portion,
In the film formation trajectory, the sum of the volumes of the measurement units in a range of a predetermined distance including the film formation start point and the film formation end point where the films overlap is the measurement of the range corresponding to the predetermined distance in the range where the films do not overlap. A film formation method that is set so that the volume of the part is the target volume . The weighing unit
a disk;
a driving unit that rotates the disk at a constant rotational speed;
2. The film forming method according to claim 1, further comprising: an annular groove formed on the upper surface of the disk, corresponding to one unit of the film forming locus of the film forming portion, and receiving the raw material powder from the hopper. . A workpiece having a film-forming portion and a nozzle of a cold spray device are relatively moved along a film-forming trajectory with respect to the film-forming portion, and raw material powder supplied from a raw material powder supply unit is sprayed from the nozzle. However, in the film forming method for forming a film on the film forming portion,
The raw material powder supply unit comprises a hopper into which the raw material powder is fed, and a weighing unit that weighs the raw material powder from the hopper into different volumes over time,
The weighing unit
a disk;
a driving unit that rotates the disk at a constant rotational speed;
an annular groove formed on the upper surface of the disk, corresponding to one unit of the film formation trajectory of the film formation target portion, and receiving the raw material powder from the hopper;
The shape is correlated with the film volume along the film formation trajectory ,
the relative movement trajectory between the workpiece and the nozzle includes a connection trajectory that connects one film formation trajectory and another film formation trajectory;
The film formation method , wherein the volume of the annular groove corresponding to the connection locus is set smaller than the volume corresponding to the other film formation loci . 4. The film forming method according to claim 2 , wherein the bottom surface of the annular groove has a depth that correlates with the film volume along the film forming trajectory. the relative movement trajectory between the workpiece and the nozzle includes a connection trajectory that connects one film formation trajectory and another film formation trajectory;
3. The film formation method according to claim 2 , wherein the volume of said annular groove corresponding to said connection locus is set smaller than the volume corresponding to said other film formation locus. 4. The film forming method according to claim 2 , wherein the weighing unit horizontally levels the upper edge of the opening of the annular groove to scrape and remove excess raw material powder.

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