| 摘要 |
PURPOSE:To provide an excellent gate cutting system which facilitates the maintenance and operation of a cutter, reduce cutting waste and the like, by a method wherein a stepped part, which corresponds to gate cutting, is provided in advance in a mold and resin is injected into a cavity and bored a hole with a ring-shaped gate cutter in the mold kept closed. CONSTITUTION:After the injection of resin into a cavity 19, the center hole of a substrate is bored with a ring-shaped gate cutter 4 in a mold kept closed. A tool angle at the outer peripheral part of the gate cutter is made to be 90 deg. or less so as to facilitate boring operation. A stepped part 20 for gate cutting is provided so as to make the volume of a gate cutting allowance nearly equal to an unfilled space 16. The gate cutter 4 is driven by an oil hydraulic part 12 for gate cutting so as to bore the cross sectional part of a product part and then further proceed to reach an anti-abutting space 18 of the gate cutter. Because the cutting edge of the gate cutter is directed inwards, the resin removed by the proceeding of the cutter flows only toward a gate part 17. Consequently, the gate part can be cut off without producing internal stress in the main body part of a disc substrate. |
