| 摘要 |
PURPOSE:To strengthen the part, which extends into a space groove part, of an upper mold and to prevent the brake of said part, by using the upper mold, where a rib is provided in the base part, to form a lower flange and a hub into one body. CONSTITUTION:A tapered reinforcing rib 14 is provided on the side of an inside cylinder part 6 of the base part of an upper mold 11B which extends into an approximately semicircular space groove part 9 between an outside cylinder part 4 and the inside cylinder part 6. By providing this rib 14, a sufficient strength is given to the partial base part extending into the space groove part 9 of the upper mold 11B even if the flow of an injected synthetic resin strikes against this base part at right angles. Though the example where the upper mold 11 and a lower mold 12 are divided into three is shown in Fig., it is unnecessary to divide always them into three, and they may be divided into two or one-body molds may be used as them. In said example, a pouring gate for injection of the synthetic resin is provided in either of the upper mold and the position of the upper mold near the center of the upper part of a hub to be formed. |
