Method of making glass ampul for jet injector

Abstract

A method of forming an ampul comprises drawing an aluminosilicate glass tube containing alkali metal ions and having the inner and outer diameter desired for the body of the ampul to reduce the diameter and provide a portion having an inner diameter in the range of from about 0.007 to about 0.03 cm. Advantageously the transition shoulder portion extending from the full diameter to the reduced diameter is heated while rotating and then subjected to axial compression to partially collapse it. The reduced diameter portion of the tube is then severed to form an ampul with a body having the inner and outer diameters of the original tube and a discharge passage which has a discharge opening with a diameter in the range of from about 0.007 to about 0.03 cm. and which has a length at least ten times the diameter of the discharge opening. The drawing provides for a small taper in the discharge passage which preferably will have a diameter equal to from about 2 to about 1 times the diameter of the discharge opening. Alternatively, the drawing operation additionally provides a portion tapering gradually to an inner diameter smaller than the desired diameter of the discharge opening and, after the severing operation, the last-mentioned portion is removed by grinding to provide a discharge opening of the desired size.

Dependencies are inferred from the claim text.