| 摘要 |
PURPOSE:To obtain a vessel in high yield from an inexpensive stock by simple work and device, by providing a slit to the central part of thickness of a thick sheet-stock by leaving its both ends, and rolling it into the prescribed width and length, and inserting a force-in rod into the split part to form a cylindrical vessel. CONSTITUTION:Chamfering 12 is provided to the corner parts of the side faces in the longitudinal direction of a thick flat-sheet stock 11 of rectangular parallelopiped having the prescribed thickness, width and length. Next, a slit 13 is cut at just the central part of stock 11 by leaving its both ends by (d) each. This cutting is easily performed by wire-cut electric discharging or fret saw cutting, even when the stock 11 is short in length. Next, the stock 11 is rolled into a flat intermediate stock 14 having the length (l1) in the longitudinal direction X, each thickness (t) of upper and lower sides and width W1. Successively, a force-in rod 15 with a pointed end is forced in between the tightly-contacting boundary surfaces 13a, to widen the clearance between them through the whole length in order to form the stock 14 into a cylindrical shape. Next, the cylindrical stock 16 is clamped between a pair of rolling rolls 18, 18' to completely flatten its projecting part 17 in order to form it into a true round shape while pressing and revolving it, thereby obtaining a perfectly cylindrical vessel 18 having the prescribed wall thickness and length. |
