HOLLOW CASTING WITH SLIT, AND MANUFACTURING METHOD AND MANUFACTURING DEVICE THEREOF

摘要

PROBLEM TO BE SOLVED: To provide a hollow casting with a slit of high quality with excellent productivity at a low cost in which core member can be easily ejected after the casting operation even when there is no draft in a core member used in casting the hollow casting with a slit, and prevent any deposition of the casting on the core surface during the ejection, and has a smooth inner surface according to the smoothness of a core surface. SOLUTION: In manufacturing a hollow casting 1 with a slit, a core 11 having a recessed part 13 (or a projecting part) on a slit forming part (or an outer circumferential part) is used, and when drawing the core out of the hollow casting, the hollow casting is released while being expanded by the recessed part (or the projecting part). The hollow casting with a slit having the projecting part (or the recessed part) formed on the slit part and/or an inner circumferential part can be obtained. Since the formed recessed part or projecting part is not brought into contact by opening/closing the slit, the performance of the product (the holding force or optical characteristics of a ferrule in a case of an optical connector part) is not affected.