A method of manufacturing a resin fan that includes a multitude of blades arranged radially from the center and held securely between a first circular plate and a second circular plate aligned at the center with each other, said resin fan being molded with resin by using a two-stage molding process, the method comprising forming a resin fan on a primary forming mold and a secondary forming mold, both of which will be described below, wherein
- (1) said resin fan is molded into a particular shape in the following way in which
- (a) said blades are so formed as to be bent and that the bend so formed has a convex surface in the direction of one complete revolution;
- (b) said blade is molded such that it has a height of H01 on the side of the outer peripheral edge thereof, said height increasing gradually toward the inner peripheral side, and that it has a height of H0 2 (>H01) on the side of the inner peripheral edge thereof;
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- (c) said first circular plate includes a first central opening portion;
- (2) said primary forming mold includes:
- (a) a first circular plate forming mold for molding the outer side and the outer peripheral edge on said first circular plate;
- (b) a first mold for molding the first central opening portion of said first circular plate;
- (c) a blade forming mold for molding said blades on the inner side of said first circular plate, in which
- (d) said blade forming mold and said first circular plate forming mold, said blade forming mold and said first mold can be moved to a molding position in which a semi-molded article including said first circular plate and said blades is to be molded by being brought closer to each other and to a non-molding position by being brought away from each other;
- (3) said secondary forming mold includes:
- (a) said first mold;
- (b) a second mold for molding said outer side and said outer peripheral edge on said second circular plate;
- (c) a third mold for molding the inner side of said second circular plate by being inserted into the corresponding gap formed between any two blades adjacent to each other and disposed radially in close proximity of the circumference of said first mold such that it can engage closely the lateral wall of one blade located in said corresponding gap and that it can engage closely the lateral wall of another blade located in said corresponding gap;
- (d) said second mold and said first mold can be moved to the molding position in which said fan is to be molded from said semi-molded article by being brought closer to each other and to the non-molding position by being brought away from each other;
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- (e) said third mold can be moved to a first position in which it is located on the centrifugal side by being brought closer to said first mold and to a second position in which it is brought away from said first mold toward the radial side, said third mold placed in said first position being inserted into the corresponding gap formed between said two blades adjacent to each other so that the inner side of said second circulate plate can be molded;
- (4) said semi-molded article and said fan are molded in the following sequence:
- (a) said blade forming mold, said first circulate plate forming mold and said first mold are closed so that they can be moved from said non-molding position to a molding position in which said semi-molded article is to be molded, and any suitable resin material is poured into said blade forming mold, said first circulate plate forming mold and said first mold for molding said semi-molded article during the primary molding stage;
- (b) said semi-molded article is moved from said primary forming mold to said first mold that forms part of said secondary forming mold;
- (c) in said first position, said third mold is inserted into each corresponding one of the gaps formed between any two adjacent blades of said semi-molded article;
- in the molding position in which said fan is to be molded, said second mold and said first mold are closed;
- and during the secondary molding stage, any suitable resin material is poured into said first mold, said second mold and said third mold so that said fan can be molded by integrally molding said second circular plate and said semi-molded article, and
- (d) said second mold and said first mold are opened so that the molding position in which said fan has been completely molded can be moved to the non-molding position and that in said second position, said third mold can be brought away from said first mold and said fan as completely molded is then removed.