| 摘要 |
PURPOSE:To provide substantial strength to a green sand core and to prevent the collapsion of the core in molding said core by inserting a rammer into the green sand to compress and harden the sand to a specific extent and removing the core from a core box in the state of leaving the rammer in the inside. CONSTITUTION:A vertically split core box 4 provided with a cavity 3 formed with apertures 1, 2 at the top and bottom ends is placed on a bottom plate 5 and green sand is blown and packed in the cavity 3. A rammer 8 of which the bottom end part is formed into a circular conical shape and the top end is connected to a lifting device is inserted into the green sand to compress the green sand at 10-50% to harden. After the rammer 8 is inserted to a prescribed depth into the cavity 3, the rammer is detached from the lifting device and when the box 4 is opened while the rammer 8 is left in the green sand, the core S having the prescribed hardness is obtd. |
