| 摘要 |
<p>A method for manufacturing cores for casting purposes in special core boxes provided with closed cavities apart from a limited filling opening through which a mixture of a sand material and a water-glass is introduced by means of a core forming machine, said filling opening having limited dimensions normally not permitting water to escape freely from an uncured core mixture in the core box. According to the invention the core boxes (20), which are constructed entirely of materials which are transparent to microwaves, are moved in a continuous and repetitious process between various treating stations comprising a core forming station (22) with a core forming machine for filling the core boxes (20) with said mixture, at least one heating station (23) having at least one microwave oven to cure the core mixture, and a removal station (28) for opening the core boxes and removing the cured core and for re-assembling the core boxes for repeated use. The core mixture in the core box is subjected during at least a final period of time of its stay in the heating station (23) to a combined and simultaneous treatment with microwaves and negative pressure so that the water present in the core mixture is caused by the raised curing temperature induced by the microwave energy supplied, to leave the core mixture through one or more evacuation openings (31, 32) in communication with a means (38, 39, 40, 41, 47) generating a negative pressure. During the combined treatment the heated water is drawn by suction action to the evacuation openings at an increased diffusion rate through the core mixture, thus enabling curing and correspondingly shortening the curing time for the core mixture.</p> |
