3 Fundamentals of press design

Presses used for solid forming
Universal press for joining, minting and punching
Based on the underlying concept of the vertical 1,500 kN minting press,
in addition to the minting of standard, multi-sided and bimetal coins,
two further application possibilities are offered:
– The press can be used to separate the rings and centers of used bimetal
coins which are being withdrawn from circulation. Separation of
the different materials offers clear advantages for recycling.
– Designed for piercing, the press permits the manufacture of outer
rings from upset coin blanks.
Normally, rings for bimetal coins are produced at high stroking rates in
multiple dies on a high-speed blanking press (cf. Fig. 4.6.6 and 4.6.8).
Due to the minimal stability of the rings, however, subsequent upsetting
is only possible to a limited degree.
Experience has shown that the reduction in diameter which takes
place here lies around 0.1 to a maximum of 0.2mm. Due to the low web
width, it may be necessary to upset the edge in several passes in order
to achieve the specified diameter. In practice, a cylindrical upsetting
shape with a 45° chamfer on each side was found to be successful
(Fig. 6.8.17).In the case of rings produced on universal presses in mints,
however, any optional upsetting shapes and edge decoration can be
used if the coin blanks are rimmed or edge lettering is carried out prior
to piercing.
Metal Forming Handbook / Schuler (c) Springer-Verlag Berlin Heidelberg 1998
Fig. 6.8.25
Titanium nitride-coated coining punches
535