| 摘要 |
PURPOSE:To facilitate the resin molding work by injecting and hardening a synthetic resin with a middle die retained at a higher temperature than an outer die employing a mold in which the middle die is arranged in the outer die defining the outer shape of a product. CONSTITUTION:A mold combines a split type outer die 25 having an inner concave defining the shape of the outer surface of, for example, a valve body 11 and provided a cooling water path 26 in the perimeter thereof and a tubular middle die 27 having a cylinderical outer surface. A cooling water flows through the path 26 of the outer die 25. Then, a valve body material is injected while a hot water is let flow with the temperature set for a internal hole 28 of the middle die 27 and retained at a specified secondary pressure. The material hardens very fast near the spherical surface 12a of the outer wall of a valve body 11 to prepare the external shell thereof. But as the center 12b of the spherical section is cooled gradually with the center 27a of the middle die, a molding shrinkage concentrates on the center 12b to obtain an internally expanded through hole 13. |
