Pipe bend die unit, and pipe bending apparatus having the unit

A pipe bending apparatus comprising:

• a bend die having a groove of half-circular cross section on an outer peripheral surface of the bend die, the bend die being rotatable about a rotary axis;
• a clamp die for clamping a pipe to be bent with the groove of the bend die;
• and
• a pressure die for pressing the pipe toward the bend die, wherein the bend die comprises:
• a clamp member having a first groove part of half-circular cross section on an outer peripheral surface of the clamp member with a fitting recess formed on the first groove part and extending in a peripheral direction by a first predetermined length on a planar surface perpendicular to the rotary axis;
• and
• a counter pressure member having a second groove part of half-circular cross section formed on an outer peripheral surface of the counter pressure member, and a fitting protrusion extending in a peripheral direction by a second predetermined length from a tip end portion of the second groove part, the fitting protrusion being positioned in the fitting recess so that the first and second groove parts combine to form the pipe-receiving groove of half-circular cross section,
• the fitting recess of the clamp member possessing width expanding end face areas, where a clearance between opposing end faces is enlarged in a predetermined distance range including at least a radially outer end portion, from the rotary axis toward a radial outside, and
• the counter pressure member and the clamp member being hingedly connected to one another about the rotary axis, and supported so as to be rotatable relative to each other about the rotary axis, to configure a pipe bend die unit.