Method for manufacturing bearing cage

A method for manufacturing a bearing cage molded by injecting a melted resin into a cavity from a plurality of resin injection gates provided at a peripheral portion of a substantially annular cavity formed in a mold, wherein,

• the bearing cage includes
• a substantially annular base portion,
• a plurality and an even number of pillars projecting in an axial direction from an axial lateral surface of the base portion at a predetermined interval in a circumferential direction, and
• pockets whose number is equal to a number of the pillars formed by mutually facing surfaces of a pair of adjacent pillars and the axial lateral surface of the base portion,
• the resin injection gates are provided in half of a plurality of the pillars respectively,
• the pillar provided with the resin injection gate and the pillar not provided with the resin injection gate are arranged alternately in the circumferential direction,
• a cross-sectional area of one resin injection gate is larger than cross-sectional areas of the other resin injection gates among a plurality of the resin injection gates,
• a resin reservoir capable of storing the melted resin is provided in:
• (a) the pillar radially facing the pillar provided with the resin injection gate having a cross-sectional area larger than those of the other resin injection gates among a plurality of the pillars not provided with the resin injection gate;
• or
• (b) the pillar in the vicinity of the pillar facing the pillar provided with the resin injection gate having a cross-sectional area larger than those of the other resin injection gates among the plurality of the pillars not provided with the resin injection gate, and
• a cross-sectional area of a communicating portion of the resin reservoir which communicates with the pillar is smaller than the smallest of cross-sectional areas of a plurality of the resin injection gates.