Engine muffler and method of manufacturing the same

摘要

This engine muffler has a sound absorbing material interposed between an internal tube and an external tube which is formed with a projection projecting toward the sound absorbing material along almost its entire periphery. When interposing the sound absorbing material between the internal tube and the external tube and drawing the end of the external tube for manufacturing the muffler, the projection projecting toward the sound absorbing material is formed on the external tube almost along its entire periphery after inserting the sound absorbing material between the internal tube and the external tube but before drawing the end of the external tube.