| 摘要 |
PURPOSE:To obtain a spongelike spherical object of high accuracy by such an arrangement wherein a spongelike base material punched out into blocklike shape is hardened by rapid freezing using a freezing agent such as liquefied nitrogen, etc. and then its square corners are ground, and then it is further ground being held between rotating parallel grindstones, and finally it is returned to its normal temperature. CONSTITUTION:A piece of spongelike base material (a) punched out by a circular cutter into blocklike shape is completely dried and it is placed on a conveyor 9 and when it comes to the position of a pushing mechanism 11, it is fixed by being thrusted by needles 5, 5 at the top end of a chuck 2 by the operation of said mechanism. Next, a holder 1 rotates and the piece of material is rapidly frozen by being immersed in a freezing agent (e.g.; liquefied nitrogen, etc.) for a fixed period of time. Next, the hardened base material is ground by grindstones 15, 15 to remove its square corners, while it is rotated, and it is pulled out of needles 5, 5 and placed on a chute 12 and guided into a space between grindstones 13, 14 and ground into a ball of a specified diameter, and after that it is taken out from the chute 18 and it is returned to its normal temperature by being heated, and a spongelike spherical object is thus obtained. |
