The present invention relates to a manufacturing method of a product having a sprayed coating film and, more particularly, to a manufacturing method of a product having a sprayed coating film on a cylindrical inner surface.
Japanese Patent Application Laid-Open Publication No. H7-62519 discloses a method of forming a sprayed coating film over a bore inner surface, as a cylindrical inner surface, of a cylinder block of an engine.
In particular, with such a method, as shown in FIG. 12, a spraying gun 3 is used which is rotated in a direction as shown by an arrow A and moved in a vertical direction as shown by an arrow B within a member 1 having a cylindrical inner surface 1a. Connected to the spraying gun 3 are a plasma spraying machine 5, a powder feeder 7, a gas cylinder 11 and a gas cylinder 13. The powder feeder 7 accommodates therein powder-like spraying material 9 and is connected to a gas cylinder 17 in which powder feed gas, such as nitrogen, helium or the like, is stored.
With such a structure, the spraying gun 3 is supplied with the powder-like spraying material 9 from the powder feeder 7. Simultaneously, while being supplied with gases, such as argon, nitrogen, helium, hydrogen or the like from the gas cylinders 11, 13, or supplied with gas suitably mixed with those gases, a plasma spraying machine 5 forms a plasma arc at a spray nozzle 3a of the spraying gun 3. And, the spraying material 9 is melted in such-a plasma arc, and the melted spraying material 9 is sprayed on to the cylindrical inner surface 1a of the member 1 to form the sprayed coating film 15 over the cylindrical inner surface 1a. 
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