Method for molding a tapered flange

Abstract

A tape reel assembly comprises a reel hub and flanges coaxially secured to, and extending radially outwardly from, opposite axial ends of the reel hub, respectively, each flange being molded by resin injection molding and having a tapered inside surface sloping down at a fixed taper angle from an inside periphery to an outside periphery thereof. The flange is molded by the use of an injection mold having a mold surface which borders at least a part of a mold cavity for configuration of the tapered inside surface of the flange and is convexly curved to the mold cavity.

1 . A method of manufacturing a flange, comprising the steps of:
 injecting a resin material into a resin injection mold assembly having a mold cavity for molding a flange of a tape reel assembly around which a recording tape is wound and which comprises a reel hub forming a cylindrical tape-winding core and at least one flange coaxially secured to, and extending radially outwardly from one of opposite axial ends of said reel hub, said flange having a tapered inside surface sloping down at a fixed taper angle from an inside periphery to an outside periphery thereof, said resin injection mold assembly comprising: i) a lower mold having a mold surface for bordering at least a lower part of said mold cavity which configures an outside surface of said flange, and ii) an upper mold having a mold surface for bordering at least an upper part of said mold cavity which configures said tapered inside surface of said flange, wherein said mold surface of said upper mold comprises a plurality of flat surface sections sloping at different taper angles gradually decreasing from said inside periphery to said outside periphery so as to be convex to said mold cavity;   cooling the injected resin material within the mold assembly; and   removing the cooled injected resin material from the mold assembly, the cooled injected resin material being a molded flange.   
     
     
         2 . The method of  claim 1 , when said mold surface of said upper mold comprises at least three said flat surface sections. 
     
     
         3 . The method of  claim 1 , wherein said mold surface of said upper mold comprises a curved surface sloping at a taper angle continuously decreasing from said inside periphery to said outside periphery. 
     
     
         4 . A method of manufacturing a flange, comprising the steps of:
 presetting a reel plate ( 54 ) in position in a mold cavity ( 206 ) of a mold assembly ( 200 ) for injection molding a hub-attached flange;   injecting a resin material into the mold cavity ( 206 ) of the mold assembly, the mold assembly comprising a lower stationary metal mold ( 202 ) and a movable upper metal mold ( 204 ) for forming a mold cavity ( 206 ) therebetween,   wherein the mold cavity ( 206 ) comprises a flange-molding cavity section ( 206 A) for a lower flange section ( 34 ) and a hub-molding cavity section ( 206 B) for a hub body ( 32 ), the movable upper metal mold ( 204 ) has a mold surface ( 220 ) which borders the flange-molding cavity section ( 206 A) to form a tapered inside surface ( 38 A) of a lower flange section ( 38 ), the stationary lower mold ( 202 ) has a mold surface ( 221 ) which borders the flange-molding cavity section ( 206 A) to form an outside surface ( 38 B) of the lower flange section ( 38 ), the stationary lower mold ( 202 ) has a plurality of injection gates ( 205 ) arranged at regular angular intervals through which the resin material is injected into the mold cavity ( 206 ), the injection gates are located correspondingly to toothless sections ( 42 A) of a reel gear ( 42 );   solidifying the injected resin material within the mold assembly; and   opening the mold assembly and removing the cooled injected resin material from the mold assembly, the cooled injected resin material being a molded hub-attached lower flange ( 72 ).   
     
     
         5 . A method of manufacturing a flange, comprising the steps of:
 injecting a resin material into a mold cavity ( 306 ) of a mold assembly ( 300 ), the mold assembly comprising a lower stationary metal mold ( 302 ) and a movable upper metal mold ( 304 ) forming a mold cavity ( 306 ) therebetween,   wherein the mold cavity ( 306 ) comprises a flange mold cavity section ( 306 A) for an upper flange section ( 38 ) and a rib-molding cavity section ( 306 B) for a rib annular rib ( 76 ), the mold assembly ( 300 ) has a plurality of injection gates ( 305 ) arranged at regular angular intervals between the lower stationary mold ( 302 ) and a movable upper metal mold ( 304 ) radially opening to the rib-molding cavity section ( 306 B), the movable metal mold ( 304 ) has a mold surface ( 320 ) which borders the flange-molding cavity section ( 306 A) to form a tapered inside surface ( 40 A) of an upper flange section ( 40 );   solidifying the injected resin material within the mold assembly; and   opening the mold assembly and removing the cooled injected resin material from the mold assembly, the cooled injected resin material being a molded ribbed upper flange.   
     
     
         6 . The method of  claim 5 , further comprising the steps of:
 presetting a reel plate ( 54 ) in position in a mold cavity ( 206 ) of a mold assembly ( 200 ) for injection molding a hub-attached flange;   injecting a resin material into the mold cavity ( 206 ) of the mold assembly, the mold assembly comprising a lower stationary metal mold ( 202 ) and a movable upper metal mold ( 204 ) for forming a mold cavity ( 206 ) therebetween,   wherein the mold cavity ( 206 ) comprises a flange-molding cavity section ( 206 A) for a lower flange section ( 34 ) and a hub-molding cavity section ( 206 B) for a hub body ( 32 ), the movable upper metal mold ( 204 ) has a mold surface ( 220 ) which borders the flange-molding cavity section ( 206 A) to form a tapered inside surface ( 38 A) of a lower flange section ( 38 ), the stationary lower mold ( 202 ) has a mold surface ( 221 ) which borders the flange-molding cavity section ( 206 A) to form an outside surface ( 38 B) of the lower flange section ( 38 ), the stationary lower mold ( 202 ) has a plurality of injection gates ( 205 ) arranged at regular angular intervals through which the resin material is injected into the mold cavity ( 206 ), the injection gates are located correspondingly to toothless sections ( 42 A) of a reel gear ( 42 );   solidifying the injected resin material within the mold assembly; and   opening the mold assembly and removing the cooled injected resin material from the mold assembly, the cooled injected resin material being a molded flange with the reel plate pre-inserted.   
     
     
         7 . The method of  claim 6 , further comprising:
 forming a reel assembly ( 10 ) by fitting the annular rib ( 76 ) of the upper flange ( 74 ) in the cylindrical hub ring section ( 34 ) of the hub-attached lower flange ( 72 ) and securing the upper flange ( 74 ) to the top of the cylindrical hub ring section  34  of the hub-attached lower flange ( 72 ).   
     
     
         8 . The method of  claim 7 , wherein, the mold surface, of the upper mold of the mold assembly ( 200 ) for injection molding a hub-attached flange, comprises a plurality of flat surface sections sloping at different taper angles gradually decreasing from an inside periphery to an outside periphery so as to be convex to said mold cavity. 
     
     
         9 . The method of  claim 8 , wherein, the flange-molding cavity section ( 206 A) has a depth (D) reducing radially outwardly from the center thereof correspondingly to the lower flange section ( 38 ) of the hub-attached lower flange ( 72 ) having a thickness decreasing from an inner side to an outer side in a radial direction.