| 摘要 |
<p>Parent patnet described mfr. of tubes by helical winding of metal strip, then joining adjacent edges of the strip by a helical welded seam obtd. using a laser beam; a second laser is then used to cut the tubes to the required length. The novelty is that the strip is fed through an oblique slot in a cylindrical sleeve and then slides over a mandrel located in the sleeve; and the laser beam passes through a hole in the sleeve to make the helical weld. The sleeve and mandrel are pref. fixed on a frame, the mandrel being shorter than its sleeve and fitted with an idling roller eccentrically mounted and supporting the edges of the strip during welding. The roller has a peripheral groove under the welding zone and filled with inert gas preventing oxidn. of the molten weld. The addn. simplifies and lowers the cost of, the process described in the parent patent.</p> |
