阅读说明：本技术 成膜方法 (Film forming method ) 是由 柴山博久 镰田恒吉 田井中直也 内海贵人 松山秀信 盐谷英尔 荻谷俊夫 铃木晴彦 于 2019-03-29 设计创作，主要内容包括：一种成膜方法,在该成膜方法中,一边使具有不相互连续的多个被成膜部(16c)的工件(3)和冷喷装置(2)的喷嘴(23d)沿着由相对于所述多个被成膜部的轨迹(T)和连结该相对于多个被成膜部的轨迹(T)的连接轨迹(CT)构成的连续的移动轨迹(MT)相对地移动,一边从所述喷嘴连续地喷射原料粉末,利用冷喷法向所述多个被成膜部分别喷射原料粉末而形成覆膜,其中,将所述移动轨迹中的所述工件与所述喷嘴之间的相对速度变低的折返点(TP1)设定于所述连接轨迹之上。(A film forming method, wherein a workpiece (3) having a plurality of film forming portions (16c) that are not continuous with each other and a nozzle (23d) of a cold spray device (2) are moved relative to each other along a continuous Movement Trajectory (MT) that is composed of a trajectory (T) for the plurality of film forming portions and a Connection Trajectory (CT) connecting the trajectories (T) for the plurality of film forming portions, while raw material powder is continuously sprayed from the nozzle, and the raw material powder is sprayed onto each of the plurality of film forming portions by a cold spray method to form a film, wherein a turning point (TP1) at which a relative speed between the workpiece and the nozzle in the movement trajectory is low is set on the connection trajectory.)

1. A film forming method in which a workpiece having a plurality of film forming portions that are not continuous with each other and a nozzle of a cold spray apparatus are relatively moved along a continuous movement locus constituted by a locus relative to the plurality of film forming portions and a connecting locus connecting the loci relative to the plurality of film forming portions, while continuously spraying a raw material powder from the nozzle,

spraying a raw material powder onto each of the plurality of film formation portions by a cold spray method to form a film,

and setting a turning point at which the relative speed between the workpiece and the nozzle in the movement locus becomes low above the connection locus.

2. The film forming method according to claim 1,

setting a turning point at which a relative speed between the workpiece and the nozzle in the movement locus becomes zero above the connection locus.

3. The film forming method according to claim 1 or 2, wherein,

the film formation part is the whole circumference of an opening part of an intake port or an exhaust port of the cylinder head,

the turning point is set above a mounting surface of the cylinder head mounted to the cylinder block.

4. The film forming method according to any one of claims 1 to 3,

at the turning point, the distance between the nozzle and the film formation part is increased.

5. The film forming method according to any one of claims 1 to 4,

a turning point set at a position upstream of a film formation starting point of the film formation section is set on the connection locus,

the turning point set at the film formation end point of the film formation section is set on a locus relative to the film formation section.

Technical Field

The invention relates to a film forming method based on a cold spraying method.

Background

The following methods for manufacturing a sliding member are known: a valve seat having excellent high-temperature wear resistance can be formed by blowing raw material powder such as metal to a seating portion of an engine valve by a cold spray method (patent document 1).

Documents of the prior art

Patent document

Patent document 1: international publication No. 2017/022505 specification

Disclosure of Invention

Problems to be solved by the invention

An automobile engine is provided with a plurality of intake valves and exhaust valves because of its multi-valve structure. Therefore, when forming valve seats on the seating portions of a plurality of valves by the cold spray method, it is necessary to move the cylinder head and the nozzle of the cold spray device relative to each other so that the seating portions and the nozzle face each other in order, and to eject and blow the raw material powder from the nozzle to the seating portion facing the nozzle.

When the cold spray device stops spraying the raw material powder, it takes a standby time of several minutes until the raw material powder is stably sprayed again. Therefore, it is desirable to perform the injection of the raw material powder as continuously as possible without interruption. However, when one valve seat film is formed, the nozzle and the cylinder head are relatively moved so as to draw a circle of 360 °, but an overlap portion is generated between the film formation start point and the film formation end point of the circular locus, or a turning point at which the moving speed of the nozzle becomes zero is generated in order to form the next valve seat film from the film formation end point.

Here, in the track of the 1 st layer where the turning point is generated at the overlapping portion, the inclination angle of the surface of the starting point of the 1 st layer becomes steep, and when the 2 nd layer is sprayed thereto, flattening of the raw material powder is inhibited, and a loose film is formed.

The present invention addresses the problem of providing a cold spray type film forming method that can suppress the formation of a loose film.

Means for solving the problems

The invention solves the problems by the following scheme: a film forming method for forming a film by continuously spraying a raw material powder along a continuous movement trajectory composed of a trajectory for a plurality of film forming portions that are not continuous with each other and a connection trajectory connecting the trajectories for the plurality of film forming portions, wherein a turning point at which a relative speed between a workpiece and a nozzle in the movement trajectory is low is set on the connection trajectory.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, since the turning point at which the relative speed between the workpiece and the nozzle in the movement locus becomes low is set on the connection locus, the turning point does not become the coating film of the 1 st layer in the overlapping portion. As a result, the formation of a loose coating film can be suppressed.

Drawings

Fig. 1 is a cross-sectional view showing a cylinder head on which a valve seat film is formed by using the cold spray device of the present invention.

Fig. 2 is an enlarged cross-sectional view of the periphery of the valve of fig. 1.

Fig. 3 is a structural diagram showing an embodiment of the cold spray apparatus of the present invention.

Fig. 4 is a front view of a spray gun showing an embodiment of a cold spray apparatus of the present invention.

Fig. 5 is a sectional view taken along line V-V of fig. 4.

Fig. 6 is a front view showing a state in which the spray gun of fig. 4 is biased.

FIG. 7 is a front view showing a film forming plant including the cold spray apparatus of the present invention.

Fig. 8 is a top view of fig. 7.

Fig. 9 is a process diagram showing a procedure for manufacturing a cylinder head using the cold spray apparatus of the present invention.

FIG. 10 is a perspective view of a cylinder head blank for forming a valve seat film using the cold spray apparatus of the present invention.

Fig. 11 is a sectional view showing an inlet port along the 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 film is formed in the intake port of fig. 12.

Fig. 14 is a cross-sectional view showing an intake port on which a valve seat film is formed.

Fig. 15 is a cross-sectional view showing the intake port after the finishing step of fig. 9.

Fig. 16 is a plan view of a cylinder head blank showing an example of a movement locus when a nozzle of a cold spray device moves over an opening of a port in a film forming method according to the present invention.

Fig. 17 is a plan view showing a moving locus of one of the intake ports in fig. 16.

Fig. 18 is a view showing a cross section of a coating film formed on the movement locus of fig. 17.

Fig. 19 is a plan view showing another example of a movement locus with respect to one intake port.

Fig. 20 is a diagram showing a movement locus of a comparative example in which a film is formed by setting a turning point at an overlapping portion between a film formation start point and a film formation end point.

Fig. 21 is a view showing a cross section of a coating film formed on the movement locus of the comparative example shown in fig. 20.

Detailed Description

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, the internal combustion engine 1 including the valve seat film to which the cold spray device of the present embodiment is preferably applied will be described. Fig. 1 is a sectional view of an internal combustion engine 1, and mainly shows the structure around a cylinder head.

The internal combustion engine 1 includes a cylinder block 11 and a cylinder head 12 assembled to an upper portion of the cylinder block 11. The internal combustion engine 1 is, for example, a gasoline engine having 4 cylinders arranged in a row, and the cylinder block 11 has 4 cylinders 11a arranged in the depth direction of the drawing. Each cylinder 11a houses a piston 13 that reciprocates in the vertical direction in the drawing, and each piston 13 is connected to a crankshaft 14 extending in the depth direction of the drawing via a connecting rod 13 a.

On a mounting surface 12a of the cylinder head 12 to the cylinder block 11, 4 concave portions 12b constituting combustion chambers 15 of the respective cylinders are formed at positions corresponding to the respective cylinders 11 a. The combustion chamber 15 is a space for combusting a mixture gas of fuel and intake air, and is formed by the recess 12b of the cylinder head 12, the top surface 13b of the piston 13, and the inner peripheral surface of the cylinder 11 a.

The cylinder head 12 includes an intake port 16 that communicates between the combustion chamber 15 and one side surface 12c of the cylinder head 12. The intake port 16 has a curved substantially cylindrical shape, and introduces intake air into the combustion chamber 15 from an intake manifold (not shown) connected to the side surface 12 c. The cylinder head 12 is provided with an exhaust port 17 that communicates the combustion chamber 15 with the other side surface 12d of the cylinder head 12. The exhaust port 17 is formed in a curved substantially cylindrical shape similarly to the intake port 16, and discharges exhaust gas generated in the combustion chamber 15 to an exhaust manifold (not shown) connected to the side surface 12 d. Further, the internal combustion engine 1 of the present embodiment is provided with two intake ports 16 and two exhaust ports 17 for 1 cylinder 11 a.

The cylinder head 12 includes an intake valve 18 that opens and closes an intake port 16 with respect to the combustion chamber 15, and an exhaust valve 19 that opens and closes an exhaust port 17 with respect to the combustion chamber 15. The intake valve 18 and the exhaust valve 19 are provided with valve stems 18a and 19a having a circular rod shape, and disk-shaped valve heads 18b and 19b provided to the tip ends of the valve stems 18a and 19a, respectively. The valve stems 18a, 19a slidably penetrate substantially cylindrical valve guides 18c, 19c, and the substantially cylindrical valve guides 18c, 19c are assembled to the cylinder head 12. Thus, the intake valve 18 and the exhaust valve 19 are movable relative to the combustion chamber 15 in the axial direction of the valve stems 18a and 19a, respectively.

Fig. 2 shows an enlarged view of a communication portion between the combustion chamber 15 and the intake port 16 and a communication portion between the combustion chamber 15 and the exhaust port 17. The intake port 16 is provided with a substantially circular opening 16a at a communication portion with the combustion chamber 15. An annular valve seat film 16b that abuts a valve head 18b of the intake valve 18 is formed on an annular edge portion of the opening portion 16 a. When the intake valve 18 moves upward along the axial direction of the stem 18a, the upper surface of the valve head 18b abuts against the valve seat film 16b to close the intake port 16. Conversely, when the intake valve 18 moves downward along the axial direction of the stem 18a, a gap is formed between the upper surface of the valve head 18b and the valve seat film 16b, and the intake port 16 is opened.

The exhaust port 17 is provided with a substantially circular opening 17a in a communication portion with the combustion chamber 15, similarly to the intake port 16, and an annular valve seat film 17b that abuts a valve head 19b of the exhaust valve 19 is formed in an annular edge portion of the opening 17 a. When the exhaust valve 19 moves upward along the axial direction of the valve stem 19a, the upper surface of the valve head 19b abuts against the valve seat film 17b to close the exhaust port 17. 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 film 17b, and the exhaust port 17 is opened. The diameter of the opening 16a of the intake port 16 is set larger than the diameter of the opening 17a of the exhaust port 17.

In the 4-cycle internal combustion engine 1, when the piston 13 descends, only the intake valve 18 is opened, and thereby the air-fuel mixture is introduced into the cylinder 11a from the intake port 16 (intake stroke). Next, the intake valve 18 and the exhaust valve 19 are closed, and the piston 13 is raised to substantially the dead center to compress the air-fuel mixture in the cylinder 11a (compression stroke). When the piston 13 reaches the substantially dead center, the compressed air-fuel mixture is ignited by the ignition plug and the air-fuel mixture is detonated. The piston 13 is lowered to the bottom dead center by the knocking, and the knocking is converted into rotational force (combustion/expansion stroke) by the coupled crankshaft 14. Finally, when the piston 13 reaches the bottom dead center and starts to rise again, only the exhaust valve 19 is opened, and the exhaust gas in the cylinder 11a is discharged to the exhaust port 17 (exhaust stroke). The internal combustion engine 1 repeats the above cycle to generate an output.

The valve seat films 16b and 17b are formed directly on the annular edge portions of the openings 16a and 17a of the cylinder head 12 by a cold spray method. The cold spraying method is as follows: a coating film is formed by causing an operating gas having a temperature lower than the melting point or softening point of the raw material powder to be a supersonic flow, introducing the raw material powder conveyed by a conveying gas into the operating gas, and spraying the raw material powder from the tip of a nozzle so that the raw material powder directly collides with the base material in a solid phase state, and plastic deformation of the raw material powder. This cold spray method has the following characteristics compared with a thermal spray method in which a material is melted and adhered to a base material: a dense coating that is not oxidized in the atmosphere is obtained, and since the thermal influence on the material particles is small, thermal deterioration is suppressed, the film formation rate is high, the film can be made thick, and the adhesion efficiency is high. In particular, since the film forming speed is high and a thick film can be formed, it is suitable for use as a structural material such as the valve seat films 16b and 17b of the internal combustion engine 1.

Fig. 3 is a view schematically showing the cold spray device 2 of the present embodiment used for forming the valve seat films 16b and 17 b. The cold spray device 2 of the present embodiment includes: a gas supply unit 21 that supplies a working gas and a carrier gas; a raw material powder supply unit 22 for supplying raw material powder of the valve seat films 16b and 17 b; and a spray gun 23 that sprays the raw material powder with a supersonic flow using a working gas below the melting point of the raw material powder; and a refrigerant circulation circuit 27 that cools the nozzle 23 d.

The gas supply unit 21 includes a compressed gas cylinder 21a, a working gas line 21b, and a carrier gas line 21 c. The working gas line 21b and the conveyance gas line 21c are respectively provided with a pressure regulator 21d, a flow rate regulating valve 21e, a flow meter 21f, and a pressure gauge 21 g. The pressure regulator 21d, the flow rate regulating valve 21e, the flow meter 21f, and the pressure gauge 21g are provided for adjustment of the respective pressures and flow rates of the working gas and the carrier gas from the compressed gas cylinder 21 a.

The working gas line 21b is provided with a heater 21i such as a band heater, and the heater 21i heats the working gas line 21b by supplying electric power from the electric power source 21h to the heater 21i through the power supply lines 21j, 21 j. The working gas is heated by the heater 21i to a temperature lower than the melting point or softening point of the raw material powder, and then introduced into the chamber 23a of the spray gun 23. The chamber 23a is provided with a pressure gauge 23b and a temperature gauge 23c, and the pressure value and the temperature value detected by the signal lines 23g and 23g are output to a controller (not shown) for feedback control of the pressure and the temperature.

On the other hand, the raw material powder supply unit 22 includes a raw material powder supply device 22a, and a metering device 22b and a raw material powder supply line 22c attached to the raw material powder supply device 22 a. The transport gas from the compressed gas cylinder 21a is introduced into the raw powder supply device 22a via the transport gas line 21 c. The predetermined amount of the raw material powder measured by the meter 22b is transferred into the chamber 23a through the raw material powder supply line 22 c.

The spray gun 23 sprays the raw material powder P, which is supplied into the chamber 23a by the carrier gas, from the tip of the nozzle 23d as a supersonic flow by the working gas, and causes the raw material powder P to collide with the base material 24 in a solid phase state or a solid-liquid coexisting state, thereby forming the coating film 24 a. In the present embodiment, the cylinder head 12 is applied as the base material 24, and the valve seat films 16b and 17b are formed by injecting the raw material powder P onto the annular edge portions of the openings 16a and 17a of the cylinder head 12 by the cold spray method.

The nozzle 23d is provided therein with a flow path (not shown) through which a refrigerant such as water flows. The nozzle 23d is provided at its distal end with a refrigerant introduction portion 23e for introducing the refrigerant into the flow path, and at its proximal end with a refrigerant discharge portion 23f for discharging the refrigerant in the flow path. The nozzle 23d cools the nozzle 23d by introducing the refrigerant into the flow path from the refrigerant introducing portion 23e, flowing the refrigerant into the flow path, and discharging the refrigerant from the refrigerant discharging portion 23 f.

The refrigerant circulation circuit 27 for circulating the refrigerant to the flow path of the nozzle 23d includes: a tank 271 that stores refrigerant; an introduction pipe 274 connected to the refrigerant introduction portion 23 e; a pump 272 connected to an introduction pipe 274 to flow the refrigerant between the tank 271 and the nozzle 23 d; a cooler 273 that cools the refrigerant; and a discharge pipe 275 connected to the refrigerant discharge portion 23 f. The cooler 273 includes, for example, a heat exchanger or the like, and cools the refrigerant by exchanging heat between the refrigerant having cooled the nozzle 23d and increased in temperature and the refrigerant such as air, water, or gas.

The refrigerant circulation circuit 27 sucks the refrigerant accumulated in the tank 271 by the pump 272, and supplies the refrigerant to the refrigerant introduction portion 23e via the cooler 273. The refrigerant supplied to the refrigerant introduction portion 23e flows from the front end side toward the rear end side in the flow path in the nozzle 23d, and exchanges heat with the nozzle 23d during this period, thereby cooling the nozzle 23 d. The refrigerant flowing to the rear end side of the flow path is discharged from the refrigerant discharge portion 23f to the discharge pipe 275, and returns to the tank 271. In this way, the refrigerant circulation circuit 27 cools the nozzle 23d by circulating the refrigerant while cooling the refrigerant, and therefore, the adhesion of the raw material powder P to the injection passage of the nozzle 23d can be suppressed.

High heat resistance and wear resistance that can withstand knocking input from the valve in the combustion chamber 15, and high thermal conductivity for cooling the combustion chamber 15 are required for the valve seat of the cylinder head 12. In response to these requirements, valve seats harder than the cylinder head 12 formed of an aluminum alloy for casting and excellent in heat resistance and wear resistance can be obtained from the valve seat films 16b, 17b formed of, for example, powder of a precipitation hardening copper alloy.

Further, since the valve seat films 16b and 17b are formed directly on the cylinder head 12, higher thermal conductivity can be obtained as compared with a conventional valve seat formed by press-fitting a seat ring of a separate component into a port opening portion. Further, as compared with the case of using a seat ring of a separate component, it is possible to achieve secondary effects such as the expansion of the throat diameter of the intake port 16 and the exhaust port 17 and the promotion of tumble flow by optimizing the port shape, in addition to the approach to the cooling water jacket.

The raw material powder P used for forming the valve seat films 16b and 17b is preferably a metal which is harder than the aluminum alloy for casting and can obtain heat resistance, wear resistance, and thermal conductivity required for a valve seat, and for example, the above-described precipitation hardening copper alloy is preferably used. As the precipitation hardening copper alloy, corson alloy containing nickel and silicon, chromium copper containing chromium, zirconium copper containing zirconium, or the like can be used. For example, a precipitation hardening copper alloy containing nickel, silicon, and chromium, a precipitation hardening copper alloy containing nickel, silicon, and zirconium, a precipitation hardening alloy containing nickel, silicon, chromium, and zirconium, a precipitation hardening copper alloy containing chromium and zirconium, or the like can be applied.

Further, a plurality of kinds of raw material powders, for example, the 1 st raw material powder and the 2 nd raw material powder may be mixed to form the valve seat films 16b and 17 b. In this case, the 1 st raw material powder is preferably a metal which is harder than the aluminum alloy for casting and can obtain heat resistance, wear resistance and thermal conductivity required for a valve seat, and for example, the above-described precipitation hardening copper alloy is preferably used. In addition, as the 2 nd raw material powder, a metal harder than the 1 st raw material powder is preferably used. For example, an alloy such as an iron-based alloy, a cobalt-based alloy, a chromium-based alloy, a nickel-based alloy, or a molybdenum-based alloy, or ceramics may be applied to the 2 nd raw material powder. Further, 1 kind of these metals may be used alone, or two or more kinds may be used in combination as appropriate.

The valve seat film formed by mixing the 1 st raw material powder and the 2 nd raw material powder harder than the 1 st raw material powder can have heat resistance and wear resistance superior to those of a valve seat film formed only of a precipitation hardening copper alloy. The reason why such an effect is obtained is considered to be that the oxide coating existing on the surface of the cylinder head 12 is removed by the 2 nd raw material powder and exposed to form a fresh interface, and the adhesion between the cylinder head 12 and the metal coating is improved. The reason for this is considered to be that the adhesion between the cylinder head 12 and the metal coating is improved due to the anchor effect caused by the insertion of the 2 nd raw material powder into the cylinder head 12. It is also considered that the reason is that when the 1 st raw material powder collides with the 2 nd raw material powder, a part of kinetic energy thereof is converted into thermal energy, or precipitation hardening of a part of the precipitation hardening copper alloy used as the 1 st raw material powder is further promoted by heat generated in the process of plastic deformation of a part of the 1 st raw material powder.

The cold spray device 2 of the present embodiment fixes the cylinder head 12 on which the valve seat films 16b and 17b are formed to the base 45, and rotates the tip of the nozzle 23d of the spray gun 23 along the annular edge portions of the openings 16a and 17a of the cylinder head 12 to spray the raw material powder. Since the cylinder head 12 is not rotated, a large space is not required, and the moment of inertia of the lance 23 is smaller than that of the cylinder head 12, the transient characteristics of rotation and the responsiveness are excellent. However, as shown in fig. 3, since the high-pressure pipe (high-pressure hose) constituting the working gas line 21b is connected to the spray gun 23, there is a possibility that the transient characteristics and responsiveness of the rotation are hindered by the deformation rigidity caused by the twisting of the hose of the working gas line 21b when the spray gun 23 is rotated. Therefore, the cold spray device 2 of the present embodiment is configured as shown in fig. 4 to 8, and improves transient characteristics and responsiveness of rotation.

Fig. 4 is a front view of a spray gun 23 showing an embodiment of a cold spray device 2 according to the present invention, fig. 5 is a cross-sectional view taken along line VI-VI of fig. 4, fig. 6 is a front view showing a state in which the spray gun 23 of fig. 4 is biased, fig. 7 is a front view showing a film forming plant including the cold spray device 2 according to the present invention, and fig. 8 is a plan view of fig. 7.

The cylinder head 12 as a workpiece is placed in a predetermined posture on a base 45 of the film forming chamber 42 of the film forming plant 4 shown in fig. 7 to 8. For example, as shown in fig. 13, the cylinder head 12 is fixed to the base 45 such that the recess 12b of the cylinder head 12 is an upper surface, and the base 45 is inclined such that a center line of the opening portion 16a of the intake port 16 or a center line of the opening portion 17a of the exhaust port 17 is in a vertical direction.

The film formation factory 4 includes a transfer chamber 41 and a film formation chamber 42 for performing a film formation process, and the film formation chamber 42 is provided with a pedestal 45 for placing the cylinder head 12 thereon and an industrial robot 25 for holding the spray gun 23. A transfer chamber 41 is provided at the front stage of the film forming chamber 42, and input and output to and from the cylinder head 12 from the outside are performed through a gate 43, and input and output to and from the cylinder head 12 between the transfer chamber 41 and the film forming chamber 42 are performed through a gate 44. For example, while the film formation process is performed on one cylinder head 12 in the film formation chamber 42, the cylinder head 12 that has completed the process before is output to the outside from the transfer chamber 41. Since the film formation process by the cold spray apparatus 2 generates noise due to a shock wave of a supersonic flow or scattering of raw material powder, other operations such as the output of the cylinder head 12 after the process and the input of the cylinder head 12 before the process can be performed simultaneously with the film formation process by performing the film formation process by providing the transfer chamber 41 and closing the door 44.

The spray gun 23 is rotatably attached to a base plate 26, and the base plate 26 is fixed to a hand 251 of an industrial robot 25 provided in a film forming chamber 42 of the film forming plant 4 shown in fig. 7 to 8. The structure of the spray gun 23 according to the present embodiment will be described below with reference to fig. 4 to 6. First, as shown in fig. 4, a holder 252 is fixed to a hand 251 of the industrial robot 25, a base plate 26 is rotatably attached to the holder 252, and the spray gun 23 is fixed to the base plate 26.

More specifically, as shown in fig. 4 and 5, a holder 252 is fixed to a hand 251 of the industrial robot 25, a main body of the motor 29 is fixed to the holder 252, and a drive shaft 291 of the motor 29 is connected to a1 st base plate 261 via a pulley and a belt, not shown, so that the 1 st base plate 261 is rotated relative to the holder. The motor 29 is reciprocally rotated within a range of, for example, a maximum of 360 °. For example, after the drive shaft 291 is rotated 360 ° clockwise with respect to the opening 16a of one intake port 16, the drive shaft 291 is rotated 360 ° counterclockwise with respect to the opening 16a of the next intake port 16, and thereafter, this operation is repeated.

The bottom plate 26 includes a1 st bottom plate 261 and a2 nd bottom plate 262, and these 1 st bottom plate 261 and 2 nd bottom plate 262 are provided to be slidable in a direction orthogonal to the rotation axis C (the left-right direction of fig. 4) by means of a linear guide 281. Then, the hydraulic cylinder 282 is driven to adjust the offset of the 2 nd base plate 262 with respect to the 1 st base plate 261, thereby setting the ejection diameter D of the film forming material.

A cover 263 is attached and fixed to the 2 nd base plate 262, and a spray gun 23 is fixed to a lower end portion of the cover 263. The spray gun 23 is fixed to the 2 nd base plate 262 via the cover 263 so that the spray direction of the nozzle 23d is directed toward the rotation axis C. However, the 2 nd base plate 262 can be offset with respect to the 1 st base plate 261 by the linear guide 281 and the hydraulic cylinder 282 described above, and therefore, the position of the tip end of the nozzle 23d of the lance 23 can be adjusted in the horizontal direction with respect to the rotation axis C.

As described above, if the position of the tip of the nozzle 23D is set to a position away from the rotation axis C as shown in fig. 6 from the line of the rotation axis C shown in fig. 4, the spray diameter D becomes smaller when the gun pitch is the same. Since the opening 16a of the intake port 16 has a larger diameter than the opening 17a of the exhaust port 17, the valve seat film 16b may be formed at the opening 16a of the intake port 16 at a position closer to the rotation axis C as shown in fig. 4, and the valve seat film 17b may be formed at the opening 17a of the exhaust port 17 at a position away from the rotation axis C as shown in fig. 6.

A working gas line 21b for guiding a high-pressure gas of 3MPa to 10MPa supplied from a compressed gas cylinder 21a shown in fig. 3 to the spray gun 23 is provided as one bundle 20 together with other piping to be discussed later, and as shown in fig. 7, hangs down from the upper part of the bottom plate 26 attached to the hand 251 of the industrial robot 25 to reach the spray gun 23. In the vicinity of the base plate 26 therebetween, as shown in fig. 4, the heater 21i is provided at the lower portion thereof while being separately connected by a swivel joint 21k such as a swivel joint. The working gas line 21b from the rotary joint 21k to the chamber 23a shown in fig. 4 is constituted by a high-pressure hose capable of withstanding a high pressure of 3MPa to 10MPa, and is arranged along the rotation axis C so as to surround the rotation axis C as shown in fig. 4. The working gas line 21b may be formed in a spiral shape in advance so as to surround the rotation axis C, for example, but a high-pressure hose that can withstand a high pressure of 3MPa to 10MPa is hard and has shape-retaining properties, and therefore, a shape-retaining mold may be provided on the outer periphery so that the high-pressure 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. 3 to the spray gun 23 is arranged around the industrial robot 25 as the tube bundle 20 shown in fig. 7, and hangs down from the upper part of the base plate 26 to reach the spray gun 23. As shown in fig. 4, the raw material powder supply line 22c is formed of a pipe including a metal pipe and a metal joint below the bottom plate 26 therebetween, and is connected to the chamber 23a of the spray gun 23.

The power supply lines 21j, 21j for guiding the electric power supplied from the electric power source 21h shown in fig. 3 to the heater 21i are arranged around the industrial robot 25 as the tube bundle 20 shown in fig. 7, hang down from the upper part of the base plate 26, and are connected to the heater 21 i. The signal line 23g for outputting the detection signal from the pressure gauge 23b shown in fig. 3 to the controller (not shown) and the signal line 23h for outputting the detection signal from the thermometer 23c to the controller (not shown) are led from the chamber 23a of the spray gun 23 to the 2 nd base plate 262 while penetrating the pipe including the metal pipe and the metal joint from the chamber 23a of the spray gun 23, and are arranged from the upper portion of the base plate 26 to the periphery of the industrial robot 25 together with the other working gas line 21b, the raw material powder supply line 22c, the power supply line 21j, and the like.

The introduction pipe 274 and the discharge pipe 275 for guiding the refrigerant supplied from the refrigerant circuit 27 shown in fig. 3 to the nozzle 23d of the spray gun 23 are disposed around the industrial robot 25 as the tube bundle 20 shown in fig. 7, hang down from the upper portion of the base plate 26, and are connected to the refrigerant introduction portion 23e at the tip end of the nozzle 23d and the refrigerant discharge portion 23f at the base end of the nozzle 23 d. As shown in fig. 4, the introduction pipe 274 and the discharge pipe 275 are formed of a pipe including a metal pipe and a metal joint below the bottom plate 26 therebetween, and are connected to the nozzle 23d of the lance 23.

As described above, the working gas line 21b formed of the high-pressure hose which is hard and has high deformation rigidity is arranged such that the rotary joint 21k thereof is arranged on the line of the rotation axis C as shown in fig. 4 and a portion below the rotary joint 21k surrounds the rotation axis C along the rotation axis C. As shown in fig. 5, the power supply lines 21j and 21j, the raw powder supply line 22C, the refrigerant introduction tube 274 and the discharge tube 275, and the signal lines 23g and 23h are disposed around the rotation axis C and at positions surrounding the working gas line 21b, except for the working gas line 21 b.

Next, a method for manufacturing the cylinder head 12 including the valve seat films 16b and 17b will be described. Fig. 9 is a process diagram showing a machining step of a valve portion in the method of manufacturing the cylinder head 12 according to the present embodiment. As shown in fig. 9, the method for manufacturing the cylinder head 12 according to the present embodiment includes a casting step S1, a cutting step S2, a cladding step S3, and a finishing step S4. In addition, for simplification of the explanation, the processing steps other than the valve portion are omitted.

In the casting step S1, the casting aluminum alloy is poured into the mold with the sand core mounted thereon, and the cylinder head blank having the intake port 16, the exhaust port 17, and the like formed in the body portion is cast and molded. The intake port 16 and the exhaust port 17 are formed by sand cores, and the recess 12b is formed by a mold. Fig. 10 is a perspective view of the cylinder head blank 3 cast and formed in the casting step S1, as viewed from the mounting surface 12a side attached to the cylinder block 11. The cylinder head blank 3 includes 4 recesses 12b, and two intake ports 16 and two exhaust ports 17 provided in the respective recesses 12 b. The two intake ports 16 and the two exhaust ports 17 of each recess 12b are grouped into 1 in the cylinder head blank 3, and communicate with openings provided on both side surfaces of the cylinder head blank 3, respectively.

Fig. 11 is a cross-sectional view of the cylinder head blank 3 taken along line XI-XI of fig. 10, showing the intake port 16. The intake port 16 is provided with a circular opening 16a exposed to the recess 12b of the cylinder head blank 3.

In the next cutting step S2, the cylinder head blank 3 is subjected to milling by an end mill, a ball end mill, or the like, and as shown in fig. 12, an annular valve seat 16c is formed in the opening portion 16a of the intake port 16. The annular valve seat 16c is an annular groove having a basic shape of the valve seat film 16b, and is formed on the outer periphery of the opening 16 a. In the method of manufacturing the cylinder head 12 according to the present embodiment, the raw material powder P is injected into the annular valve seat portion 16c by the cold spray method to form a coating, and the valve seat film 16b is formed on the basis of the coating. Therefore, the annular valve seat portion 16c is formed to have a size one turn larger than the valve seat film 16 b.

In the coating step S3, the raw material powder P is injected into the annular valve seat portion 16c of the cylinder head blank 3 by the cold spray device 2 of the present embodiment, thereby forming the valve seat film 16 b. More specifically, in the coating step S3, as shown in fig. 13, the cylinder head blank 3 is fixed and the spray gun 23 is rotated at a constant speed so that the raw material powder P is blown over the entire circumference of the annular valve seat 16c while keeping the annular valve seat 16c and the nozzle 23d of the spray gun 23 at the same posture and at a constant distance.

The tip of the nozzle 23d 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. As shown in fig. 4, the base 45 or the industrial robot 25 sets the position of the cylinder head 12 or the spray gun 23 so that the center axis Z of the intake port 16 on which the valve seat film 16b is to be formed is perpendicular to and overlaps the rotation axis C. In this state, while the raw material powder P is blown from the nozzle 23d to the annular valve seat 16C, the spray gun 23 is rotated around the C axis by the motor 29, and a coating film is formed on the entire circumference of the annular valve seat 16C.

While the coating step S3 is being performed, the nozzle 23d introduces the refrigerant supplied from the refrigerant circuit 27 into the flow path from the refrigerant introducing portion 23 e. The refrigerant cools the nozzle 23d while flowing from the front end side to the rear end side of the flow path formed inside the nozzle 23 d. The refrigerant flowing to the rear end side of the flow path is discharged from the flow path by the refrigerant discharge portion 23f and is collected.

When the spray gun 23 rotates 1 rotation around the C axis and the formation of the valve seat film 16b is completed, the rotation of the spray gun 23 is temporarily stopped. During this rotation stop, the industrial robot 25 moves the spray gun 23 so that the central axis Z of the intake port 16, on which the valve seat film 16b is to be formed next, coincides with the reference axis of the industrial robot 25. After the movement of the spray gun 23 by the industrial robot 25 is completed, the motor 29 restarts the rotation of the spray gun 23 to form the valve seat film 16b on the next intake port 16. Thereafter, by repeating this operation, valve seat films 16b and 17b are formed on all the intake ports 16 and the exhaust ports 17 of the cylinder head blank 3. When the object of forming the valve seat film is switched between the intake port 16 and the exhaust port 17, the inclination of the cylinder head blank 3 is changed by the base 45.

Fig. 16 is a plan view of the cylinder head blank 3 showing an example of the movement locus MT when the nozzle 23d of the cold spray device 2 moves to the opening portions of the intake port 16 and the exhaust port 17 in the film forming method of the present invention. The nozzle 23d is relatively moved along a movement locus MT indicated by an arrow with respect to the opening portions 16a of the 8 intake ports 16 and the opening portions 17a of the 8 exhaust ports 17 of the cylinder head blank 3 shown in fig. 16. Note that, although the movement locus MT with respect to the intake port 16 will be described below, the movement locus with respect to the exhaust port 17 is also set in the same manner.

As described above, after the nozzle 23d is rotated clockwise by 360 ° with respect to one intake port 16, it is rotated counterclockwise by 360 ° with respect to the next intake port 16. Then, the nozzle 23d moves while repeating clockwise rotation and counterclockwise rotation with respect to the 8 intake ports 16. That is, the nozzle 23d rotates counterclockwise with respect to the openings 16a8, 16a6, 16a4, and 16a2 of the 4 intake ports shown in fig. 16, and rotates clockwise with respect to the openings 16a7, 16a5, 16a3, and 16a1 of the remaining 4 intake ports.

The movement locus MT for the 8 intake ports 16 is constituted by a circular locus T for each annular valve seat 16c of each intake port 16 and a connecting locus CT connecting adjacent circular loci T to each other, and is a series of continuous loci. The nozzle 23d is moved along the movement trajectory MT while continuously ejecting the raw material powder from the nozzle 23d without interruption. The circular trajectory T of the one annular valve seat 16c starts from the film formation starting point, moves clockwise or counterclockwise, and then overlaps at the film formation starting point, and the overlapping portion is set as the film formation end point.

Fig. 20 is an enlarged plan view of a movement locus MT of a comparative example with respect to the opening 16a8 of the one intake port 16 positioned at the lower right in fig. 16. Since the nozzle 23d is rotated counterclockwise with respect to the annular valve seat 16c of the opening portion 16a8 of the intake port 16, the movement locus MT of the comparative example shown in fig. 20 is the following locus: the nozzle 23d is linearly moved from the right end to the left in fig. 20 to the annular valve seat 16c, and after the nozzle 23d is rotated counterclockwise on the circular trajectory T with this as the film formation start point, the orientation is changed at the film formation end point overlapping with the film formation start point, and the nozzle 23d is moved in the left direction in fig. 20. In the movement trajectory MT of the comparative example, a turning point TP1 at which the movement speed of the nozzle 23d becomes zero occurs at the film formation start point of the annular valve seat 16c, and a turning point TP2 at which the movement speed of the nozzle 23d becomes zero occurs at the film formation end point. The turning points TP1 and TP2 are points on the movement locus MT at which the movement speed of the nozzle 23d becomes zero or a value close to zero, and are points at which the movement locus changes at a right angle or an acute angle (≦ 90 °).

Fig. 21 is a view showing a cross section of a coating film at an overlapping portion when a film is formed on the movement locus MT of the comparative example of fig. 20. At the 1 st turn point TP1 generated at the film formation start point, the velocity of the nozzle 23d is temporarily zero, but the raw material powder injection is continued, so the end portion inclination S of the valve seat film 16b1 constituting the 1 st layer becomes steep as shown in fig. 21. Since the cold spray method is used to cause the raw material powder to collide with the base material directly in a solid phase at supersonic speeds and to be plastically deformed, if the layer 2 is sprayed onto the surface of the layer 1 having a steep end slope S, the raw material powder of the layer 2 is not sufficiently flattened, and the pore diameter in the layer of the valve seat film 16b2 of the layer 2 becomes large. The reason for the disadvantage of the increase in the void ratio caused by such a shortage of the flattening ratio is that the end portion inclination S of the valve seat film 16b1 constituting the 1 st layer becomes steep. In other words, if the 1 st layer includes a turning point in a range (including an end point) from the film formation start point to the film formation end point in the circular trajectory of the annular valve seat 16c as the film formation target portion, the end portion inclination S becomes steep at the turning point. However, even if the trace of the layer 2 of the overlap portion includes the turning point, the problem of insufficient flattening does not occur as long as the end portion inclination S of the valve seat film 16b2 of the layer 1 is not steep.

Therefore, in the film forming method of the present embodiment, the turning point TP1 is set not on the circular trajectory T but on the connection trajectory CT so as not to include the turning point TP1 on the 1 st layer of the circular trajectory T. Fig. 17 is a plan view showing a movement locus MT with respect to the opening 16a8 of the one intake port 16 of fig. 16. The movement trajectory MT of this example shown in fig. 17 is the following trajectory: the cylinder head blank 3 is attached to the attachment surface 12a of the cylinder block 11 by linearly moving the nozzle 23d from the right end to the left in fig. 17 to the lower left of the annular valve seat 16c, and this is set as the turn-back point TP1 of the layer 1. Then, the orientation is changed at the turning point TP1, the nozzle 23d is moved in the diagonally upward and rightward direction toward the annular valve seat 16c, the nozzle 23d is rotated counterclockwise on the circular trajectory T with this set as the film formation start point, the film formation end point overlapping with the film formation start point is set as the turning point TP2 of the layer 2, and the nozzle 23d is moved in the leftward direction of fig. 20.

Fig. 18 is a view showing a cross section of a coating film at an overlapping portion in the case where the film is formed along the movement trajectory MT of fig. 17. When the overlap portion of the annular valve seat portion 16c is observed, the moving speed of the nozzle 23d becomes a speed other than zero at the film formation start point of the valve seat film 16b1 of the layer 1, and therefore, the surface of the valve seat film 16b1 of the layer 1 is formed flat. Therefore, even if the valve seat film 16b2 of the layer 2 that is the film formation end point overlaps the valve seat film 16b1, the collision direction is substantially perpendicular to the surface of the valve seat film 16b1 of the layer 1, and therefore the raw material powder of the layer 2 is sufficiently flattened and the pore diameter in the layer of the valve seat film 16b2 is sufficiently reduced. Further, although the turning point TP1 of the 1 st layer which may become the overlap portion, that is, the turning point set at the position on the upstream side of the film formation starting point of the annular valve seat portion 16c is set above the connection locus CT, the end inclination S of the turning point TP2 of the 2 nd layer which becomes the overlap portion may become steep, and therefore, the turning point TP2 is set above the circular locus T.

Incidentally, when the nozzle 23d is relatively moved along the movement trajectory MT of the present example shown in fig. 17, the distance between the nozzle 23d and the mounting surface 12a of the cylinder head blank 3, the so-called gun pitch, may be increased at the turning point TP1 set above the connection trajectory CT. In this case, the gun distance may gradually increase as the gun distance approaches the turning point TP1, and then gradually return to the original gun distance as the gun distance moves away from the turning point TP 1. By increasing the gun pitch between the nozzle 23d and the mounting surface 12a, the film thickness of the excess coating film formed on the mounting surface 12a becomes thinner, and therefore the removal depth of the excess coating film in the finishing step S4 can be made shallower.

Fig. 19 is a plan view showing another example of the movement locus MT with respect to the opening 16a8 of one intake port 16. In the movement trajectory MT shown in fig. 17, the turn-back point TP2 of the 2 nd floor is set above the circular trajectory T with respect to the annular valve seat 16c, but may be set above the mounting surface 12a of the cylinder head blank 3 as shown in fig. 19, similarly to the turn-back point TP1 of the 1 st floor.

Returning to fig. 9, in the finishing step S4, the valve seat films 16b and 17b, the intake port 16, and the exhaust port 17 are finished. In the finish machining of the valve seat films 16b, 17b, the surfaces of the valve seat films 16b, 17b are cut by milling using a ball end mill, and the valve seat film 16b is adjusted to a predetermined shape. 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 a machining line PL shown in fig. 14. The processing line PL is a range in which an excess coating SF formed by scattering and adhering the raw material powder P into the intake port 16 is formed to be relatively thick, more specifically, a range in which the excess coating SF is formed to be thick to such an extent that the excess coating SF affects the intake performance of the intake port 16.

In this way, the surface roughness of the intake port 16 due to the cast molding is removed in the finishing step S4, and the excess coating SF formed in the coating step S3 can be removed. Fig. 15 shows the intake port 16 after the finishing step S4. Similarly to the intake port 16, the exhaust port 17 is formed with a valve seat film 17b by forming a small-diameter portion in the exhaust port 17 by casting, forming an annular valve seat portion by cutting, and cold spraying and finishing the annular valve seat portion. Therefore, the step of forming the valve seat film 17b on the exhaust port 17 is not described in detail.

As described above, the film formation method using the cold spray apparatus 2 according to the present embodiment is a film formation method including: in a film forming method for forming a valve seat film 16b by continuously ejecting a raw material powder from a nozzle 23d while relatively moving the cylinder head blank 3 having a plurality of annular valve seats 16c not continuous with each other and the nozzle 23d of a cold spray device 2 along a continuous movement trajectory MT formed of a circular trajectory T with respect to the annular valve seats 16c and a connection trajectory CT connecting the plurality of circular trajectories T, and respectively ejecting the raw material powder to the plurality of annular valve seats 16c by a cold spray method, a turning point 1 at which a relative speed between the cylinder head blank 3 and the nozzle 23d in the movement trajectory MT becomes a value of zero or close to zero is set not on the circular trajectory T but on the connection trajectory CT. Thus, even if the valve seat film 16b2 of the layer 2 that is the film formation end point overlaps the valve seat film 16b1, the collision direction is substantially perpendicular to the surface of the valve seat film 16b1 of the layer 1, and therefore the raw material powder of the layer 2 is sufficiently flattened and the pore diameter of the pores in the layer of the valve seat film 16b2 is sufficiently reduced.

In the film forming method using the cold spray apparatus 2 according to the present embodiment, the entire circumference of the opening portions 16a and 17a of the intake port 16 and the exhaust port 17 of the cylinder head 12 is set as a film formation target portion, and the turning point TP1 is set on the mounting surface 12a of the cylinder head blank 3 to be mounted on the cylinder block 11. Thus, the excess coating formed on the mounting surface 12a of the cylinder head blank 3 attached to the cylinder block 11 along the connecting trajectory CT can be easily removed together with other portions in the finishing step S4, which is a subsequent step.

According to the film forming method using the cold spray apparatus 2 of the present embodiment, since the gun pitch between the nozzle 23d and the cylinder head blank 3 is increased at the turning point TP1, the film thickness of the excess coating film formed on the mounting surface 12a becomes thin, and the removal depth of the excess coating film in the finishing step S4 can be made shallow.

According to the film formation method using the cold spray apparatus 2 of the present embodiment, the turning point TP2 set at the film formation end point of the annular valve seat 16c is set on the circular trajectory T with respect to the annular valve seat 16 c. The turning point set at the position upstream of the film formation starting point of the annular valve seat 16c is set on the connecting trajectory CT, but the inclination S of the end portion of the turning point TP2 of the 2 nd layer in the overlapping portion may become steep, and therefore, the turning point TP2 can be set on the circular trajectory T.

The annular valve seat 16c corresponds to a film formation target portion of the present invention.

Description of the reference numerals

1. An internal combustion engine; 11. a cylinder block; 11a, a cylinder; 12. a cylinder head; 12a, a mounting surface; 12b, a recess; 12c, 12d, side; 13. a piston; 13a, a connecting rod; 13b, a top surface; 14. a crankshaft; 15. a combustion chamber; 16. an air inlet; 16a, an opening; 16b, a valve seat film; 16c, an annular valve seat; 17. an exhaust port; 17a, an opening; 17b, a valve seat film; 18. an intake valve; 18a, a valve stem; 18b, a valve head; 18c, a valve guide; 19. an exhaust valve; 19a, a valve stem; 19b, a valve head; 19c, valve guide; 2. a cold spraying device; 21. a gas supply unit; 21a, a compressed gas cylinder; 21b, a working gas line; 21c, a conveying gas pipeline; 21d, a pressure regulator; 21e, a flow regulating valve; 21f, a flow meter; 21g, a pressure gauge; 21h, a power source; 21i, a heater; 21j, a power supply line; 21k, a rotary joint; 22. a raw material powder supply unit; 22a, a raw material powder supply device; 22b, a meter; 22c, a raw material powder supply line; 23. a spray gun; 23a, a chamber; 23b, a pressure gauge; 23c, a thermometer; 23d, a nozzle; 23e, a refrigerant introducing part; 23f, a refrigerant discharge portion; 23g, signal lines; 24. a substrate; 24a, coating a film; 25. an industrial robot; 251. a hand; 252. a support; 26. a base plate; 261. 1, a bottom plate; 262. a2 nd base plate; 263. a cover; 27. a refrigerant circulation circuit; 271. a tank; 272. a pump; 273. a cooler; 274. an introducing pipe; 275. a discharge pipe; 28. a biasing mechanism; 281. a linear guide; 282. a hydraulic cylinder; 29. a motor; 291. a drive shaft; 3. a cylinder head blank; 4. a film forming plant; 41. a delivery chamber; 42. a film forming chamber; 43. 44, a door; 45. a base; MT, movement trajectory; t, a track of the film forming part; CT1, CT2, connecting track; TP1, TP2, a turning point; s, the end part is inclined.