Coated article, manufacturing method therefor and coating apparatus

A method for manufacturing a coated gear, comprising the steps of:

• depositing a powder coating material having a particle size of 10 to 70 μm onto a gear by electrostatic powder coating process to form a primary powder bed on a surface of the gear;
• removing the powder bed from crests of teeth of the gear by a specified thickness by scraping the powder bed with a scraper while sucking up the scraped powder;
• further depositing a powder coating material having a particle size of 10 μm to 70 μm over the surface of the gear by electrostatic powder coating process to form a secondary powder bed;
• and
• melting the primary and secondary powder beds by electromagnetic induction heating to form a coating film having a thickness of 150 μm to 200 μm.

A method for manufacturing a coated spline shaft, comprising the steps of:

• forming a thermoplastic resin-based primary powder bed on a surface of a toothed portion of a spline shaft by electrostatic powder coating process;
• removing the powder bed from crests of teeth in the toothed portion of the spline shaft by a specified thickness by scraping the powder bed with a scraper movable in an axial direction of the spline shaft while sucking up the scraped powder by a suction means;
• further coating the toothed portion of the spline shaft with a thermoplastic resin-based secondary powder bed by electrostatic powder coating process;
• and
• melting the primary and secondary powder beds by electromagnetic induction heating to form a coating film.

A method for forming a coating film on an article to be coated, said article having a region containing projections and depressions defined by or defining the projections, comprising the steps of:

• performing electrostatic powder coating process to form a primary powder bed in said region of the article to be coated;
• removing the primary powder bed from a tip portion of each projection by a specified thickness;
• performing electrostatic powder coating process to form a secondary powder bed over said region from which the primary powder bed at the tip portions of the projections has been removed by the specified thickness;
• and
• melting the primary and secondary powder beds by induction heating to form a coating film in said region of the article, said coating film having a substantially uniform film thickness at any portion thereof.

A coating apparatus comprising:

• coating means performing electrostatic powder coating on an article to be coated having a region containing projections and depressions defined by or defining the projections, to form a primary powder bed on a surface of the article in said region;
• scraper means removing the powder bed from a tip portion of each projection of the article;
• coating means performing electrostatic powder coating on the article from which the powder bed at the tip portions of the projections has been removed by the scraper means, to form a secondary powder bed over the entire surface of the article in said region;
• and
• induction heating means melting the primary and secondary powder beds.