| 摘要 |
<p>Methods for foming a rib (118) on a cannula (18) for cooperation with a safety cover (20) which securably and reliably locks the tip (116) of a cannula in an interior chamber (104) within the safety cover. The cover comprises an elongate body having the interior chamber and an axial through hole (100) which extends along the entire length of the body, through the interior chamber and through which the cannula is slidably received. Displacing elements (108,110,120,122) are positioned within the interior chamber, each of which includes a hole (112,114,124,126) for receiving the cannula therethrough, and which displaces upon retraction of the tip of the cannula, thereby preventing subsequent advancement of the cannula tip. The cannula includes a thickened rib (118) adjacent to the tip, and the safety cover should correspondingly include an annular section (107) in the rear portion thereof. The through hole (105) extending through the rear portion has a diameter which is smaller than the thickened rib of the cannula whereby the cannula tip may not be retracted from the safety cover. The rib is formed by a thermal method in which a sleeve is heated to expand its inside diameter to allow the sleeve to be slid onto the cannula. The sleeve is then cooled to room temperature so that the inside diameter contracts to attach the sleeve to the cannula. In another method, a sleeve is placed on the cannula and crimped at the desired location.</p> |
