Abstract: A muffler is provided including a pair of internal plates formed to define an array of tubes. At least one external shell is formed to define at least one chamber which will surround and enclose a selected portion of the array of tubes. Selected portions of certain tubes will be formed to include perforations. Portions of certain tubes will further undergo cross-sectional changes to control the flow of exhaust gases through the muffler. Certain channels between adjacent chambers of the external shell will be disposed to extend substantially continuously from peripheral portions of the adjacent chambers formed in the external shell. In certain embodiments, a controlled communication is provided between a low frequency resonating chamber and an adjacent expansion chamber. In other embodiments, additional formed layers are provided to enhance either heat or noise insulation.

Abstract: The disclosure embraces a method of and apparatus for expanding circular cylindrical metal tubing, pipe or tubular members wherein an expanding construction embodies expandable fingers or members and cone-shaped means cooperating with the fingers or members for expanding tubing, pipe or tubular members. The method and apparatus involves the use of power means for expanding the fingers by relative movement of cones engaging the fingers, the method and apparatus including selectable indexing means for determining the amount of expansion of tubing, pipe or tubular members.