| 摘要 |
<p>The invention relates to a method for making tubes formed with holes in their peripheral wall, particularly muffler tubes, in which the tubes are formed of sheet metal and subsequently welded along abutting edges of the sheet metal. Known from practical application is a method of the type defined above, in which a hole pattern is initially punched into a sheet metal strip. The metal strip is subsequently formed, as by a roll forming method, into tubes which are then closed by a longitudinal weld seam. After the welding step the tubes are cut to length by means of a cutting device, the operation of which is controlled depending on the hole pattern. It is the object of an invention to provide a method and apparatus of the type defined above which in addition to the advantage of economical production offers the possibility of forming the tubes with holes over their entire periphery. With regard to the method according to the invention, this object is attained by introducing a backing element into the previously welded tube and forcing it into engagement with the interior wall surface thereof, followed by the formation of holes from the exterior in the area of the tube supported by the backing element.</p> |
