定義

• Die Camber.  A slightly domed or convex curvature of the table or background in a die. The die is purposefully domed so it may strike coins that are slightly concaved or basin shaped. The theory is that this camber will lower all of the relief below that of all the rim, thus with all design lower than the rim, it will reduce wear on the design while the coin is in circulation. The rim bears the brunt of all surface wear (until the rim itself is worn down to the level of the design).
  Placing the camber in the die is intentional. It is often so slight that it is hardly
  noticeable to the human eye. Some mints require their artists to model a design on
  a basin-shaped background plate to create this camber in the model. Numismatic writer Walter Breen called the creating of die camber basining and described it as “imparting variable radius of curvature to the fields.”
  However, with the modern die-engraving pantograph, particularly the Janvier, a die can be cut with a camber from a flat pattern. Thus the die, hub or master die can be made with the desired camber from a flat model or pattern on a modern pantograph. The total surface – device and lettering in addition to the fields – is lowered, ever so slightly near the rim, gradually increasing towards the center point.
  It is impossible to know how the basin shape was created on a coined piece by
  inspection alone (unless the coined surface is badly buckled by sinking). This condition may have resulted from any of the following:  (1) use of an intended basin-shaped model, (2) die camber created by the pantograph, or (3) sinking in a worn die.
  Die camber is different from a cone blank or dome blank which is the contour of a die prior to its being hubbed. It is also different from a buckled die, or sunken die, in old or worn dies. Sinking occurs in all dies ever so slowly from constant compaction during striking (badly sunken dies strike pieces with an irregular domed effect).
  References:                                                                                                                             
  NC10 {1988} Breen, p 524-525.

  excerpted with permission from

  An Encyclopedia of Coin and Medal Technology

  For Artists, Makers, Collectors and Curators

  COMPILED AND WRITTEN BY D. WAYNE JOHNSON

  Roger W. Burdette, Editor

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