Tool Actuating Force Transmitted By Pattern Patents (Class 234/78)
  • Patent number: 4616540
    Abstract: 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.
    Type: Grant
    Filed: May 9, 1984
    Date of Patent: October 14, 1986
    Inventor: Alfred Morhard