Terminal crimping apparatus

1. A terminal crimping apparatus comprising:

an anvil for supporting a metal terminal including a base plate portion for placing an electric wire thereon and a pair of crimping piece portions extending upwardly respectively from opposite side edges of the base plate portion; and

a crimper which includes a press-deforming portion having a generally arch-shape formed of two arc-shaped surfaces which are opposed to the anvil,

wherein the anvil and the crimper cooperate to press the crimping piece portions for crimping the crimping piece portions to the electric wire placed on the metal terminal; and

wherein the shape of the crimper satisfies a formula, Index a=c·cos θ, where c represents a length of the arc-shaped surface of the crimper, and θ represents an angle formed by a tangential line to the arc-shaped surface at a central portion of the crimper and a vertical line,

the Index a=c·cos θ is within the range of from 0.7 to 0.85 (0.7≦a≦0.85),

the metal terminal is crimped to the electric wire having a cross-sectional area of 0.08 to 0.13 mm 2 ,

the metal terminal is crimped to the electric wire made of a copper alloy,

the quantity Index a equals a vector quantity acting in a downward vertical direction on the crimping piece portions,

c represents a vector quantity acting in a direction tangential to the arc-shaped surface of the crimper and toward the central portion of the crimper; and

a vector quantity b represents a vector quantity acting in a horizontal direction such that the vector quantity b plus the vector quantity a equals the vector quantity c(b+a=c), vector quantity b having a value greater than zero.