| 摘要 |
In a tube fitting a nut which extends about the end of a tube allows the tube to be threadedly joined to a nipple. The end of the tube is formed in the shape of a collar which retains the nut. The face of the collar is flattened to sealingly meet with an o-ring which resides in an annular recess in the frontal surface of the nipple. The process of forming the collar in the end of the tube includes placing a nut on the tube, gripping the end of the tube with a die, and deforming the end of the tube with a tool of truncated cone-shape move in an advancing, precessing motion. The die is shaped with interior shoulders having the profile of the collar. A socket which forms the back side of the collar can be placed over the tube after the die grips the tube. After the collar formed the dies is removed.
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