Congressional Edition Volume 5347
This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1907 edition. Excerpt: ... mechanism interferes in no way with the other movements or speed of the press and may be applied to any of our coining presses of the large size, and if the coinage is continued it will be necessary to equip the other mints with similar devices. HOPPER FEEDS ON UPSETTING MACHINES. One of the mechanical operations required in the manufacture of coin is that of rolling or upsetting the edge of the blank to thicken it at its circumference. This is done by passing the blank between a revolving disk and a stationary segment, each of which has corresponding grooves so shaped that a border of the proper shape will be formed. Until recently these machines were fed from tubes by a revolving feeder, and some of the most expert women could feed, from 600 to 700 blanks per minute. During the last two years a new automatic feeding device has been attached to several of these machines. This mechanism will feed 1,000 coins per minute, and one person can easily keep two machines charged, making a gain in the output per person of 166 per cent. ANNEALING. All gold, silver, nickel, and copper strip annealing in this department has been dispensed with. Better percentages are obtained from cold rolling, and blistered metal is now unknown. Out of all strips two and three blanks are cut at one stroke. Double-staggered punches are now in use, and since their introduction less metal in the way of clippings is returned to the melting pot. The percentages from the ingot rolled cold and the blanks cut therefrom with the new-style punches will be about 66 per cent. In eagles we have reached as high as 70 per cent. From the cut blanks in double eagles we get about 93 per cent and eagles as high as 97 per cent. In silver, which is not adjusted but only weighed after...
- 189 x 246 x 8mm | 272g
- 13 Sep 2013
- United States
- black & white illustrations