Patent ID: 11862376
Assignee: MURATA MANUFACTURING CO., LTD.
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC H | IPC H

Claim 8:
9. A method of manufacturing the core according to claim 4, the method comprising:
providing a die, an upper punch, and a lower punch;
forming a compact by pressing a ceramic powder, the compact being formed into the core;
firing the compact; and
polishing the fired compact, wherein
the forming the compact includes pressing the ceramic powder filled in a cavity of the die by moving the upper punch and the lower punch closer to each other with the ceramic powder interposed therebetween,
inside the cavity, the die includes a first molding face that serves to form a first side surface extending between the first corner portion and the second corner portion of the winding core portion and also includes a second molding face that serves to form a second side surface extending between the third corner portion and the fourth corner portion of the winding core portion,
the upper punch includes a third molding face that serves to form an upper surface extending between the first corner portion and the fourth corner portion of the winding core portion,
at the first corner portion, the third molding face includes a face that serves to form a first shoulder that is a portion to be formed into the second round surface and a first concave face that serves to form the first round surface at a position inside the first shoulder,
at the fourth corner portion, the third molding face also includes a face that serves to form a fourth shoulder that is a portion to be formed into the second round surface and a fourth concave face that serves to form the first round surface at a position inside the fourth shoulder,
the lower punch includes a fourth molding face that serves to form a lower surface extending between the second corner portion and the third corner portion of the winding core portion,
at the second corner portion, the fourth molding face includes a face that serves to form a second shoulder that is a portion to be formed into the second round surface and a second concave face that serves to form the first round surface at a position inside the second shoulder,
at the third corner portion, the fourth molding face also includes a face that serves to form a third shoulder that is a portion to be formed into the second round surface and a third concave face that serves to form the first round surface at a position inside the third shoulder,
the compact obtained by the forming the compact has the first shoulder and the first round surface that are formed at the first corner portion, the second shoulder and the first round surface that are formed at the second corner portion, the third shoulder and the first round surface that are formed at the third corner portion, and the fourth shoulder and the first round surface that are formed at the fourth corner portion, and
the polishing the fired compact includes forming the second round surfaces respectively at the first shoulder, the second shoulder, the third shoulder, and the fourth shoulder by polishing the first shoulder, the second shoulder, the third shoulder, and the fourth shoulder.