| 摘要 |
<p>A method and apparatus for reducing the cross-section of a terminal portion of a tubular body 14 said apparatus comprising an external die 20 which defines a convergent work surface therein of like shape to the exterior of the reduced cross-section 17/19 to be produced; a plug 22 having a work surface 23 thereon of like shape to the interior of the reduced cross-section to be produced; means 27,28 to hold the plug in axial alignment with the die during relative motion as between the plug 21 and die 20 to centre the plug within the die to define a pass gap of shape and gap width substantially equal to that shape and thickness of the reduced cross-section; means 24 to enter the terminal portion of the tubular body 14 into the pass gap between the plug and die; and means 25,26 to cause the die to vibrate in a radial mode at an ultrasonic frequency while the terminal portion is progressively reduced to the shape of the pass gap.</p> |
