Metal tube and apparatus and method for manufacturing the same

摘要

A thin-walled metal tube includes a tubular nipple section, a shoulder section joined to the nipple section, a tubular barrel section and a border section connecting the shoulder and barrel sections, the barrel section being defined by a wall having a thickness in the range of between about 20 microns and about 70 microns. The border section includes a region which changes in thickness, the wall thickness of the border section being greater than the thickness of the wall defining the barrel section and the thickness changing region having a cross-section having either an arcuate or a tapered region. Apparatus for manufacturing the thin-walled tube includes a punch having a main shank, a punch head and an extruding corner therebetween having the largest diameter of the punch and a die adapted to cooperate with the punch in a single impact extrusion operation, the die having a recess defined by a side surface, a first bottom surface for forming the shoulder section and the border section of the tube and a second bottom surface for forming the nipple section of the tube. An angle is defined between the punch axis and a line tangent to the surface of the punch head at the extruding corner which is in the range of about 130 DEG to about 170 DEG . The punch and die are formed so that upon the punch reaching the end of its stroke wherein it is located within the die recess, the distance between the surface of the punch head and the first bottom surface of the die is greater than the distance between the extruding corner of the punch and the side surface of the die.