Portable beverage container with ultrasonic welded joint and method of making the same

An insulated drinking vessel comprising a generally cylindrical outer vessel and a generally cylindrical inner vessel, each of said vessels being blow molded of a plastic material, said outer vessel having a sidewall from which a first flange projects outward, said first flange having an undersurface adapted for engagement by a separate support structure, said inner vessel having a sidewall from which a second flange projects, said first flange including an annular wall upstanding therefrom, said annular wall having a predetermined height and being formed by a pair of sidewall surfaces tapering toward each other at a slight angle, said annular wall terminating in a top surface, said second flange including an engagement surface having an annular groove to receive said annular wall to form a permanent welded joint, a first part or top of said annular groove being formed by a pair of sidewalls which are parallel to each other and separated from each other by a distance slightly less than the distance separating said sidewall surfaces of said annular wall at said top surface of said annular wall, a second part of said annular groove having a chamfered entryway contiguous with said engagement surface, said inner vessel being disposed within said outer vessel, with said first and second flanges juxtaposed to each other so that said inner vessel is supported by said first flange of said outer-vessel, with a portion of said annular wall contiguous with said end surface of said annular wall being received within said chamfered entryway, said undersurface of said first flange of said outer vessel being adapted to be engaged and suspended by a support structure so that said inner vessel and said outer vessel can be ultrasonically welded together while so suspended, and wherein said second flange has a surface that is adapted to be engaged with an ultrasonic welding device, whereupon ultrasonic energy can be applied thereto and concentrated thereat to ultrasonically weld said inner vessel and said outer vessel together so that said annular wall extends through said chamfered entryway and fully enters said first part of said annular groove to thereby create said permanent welded joint, said permanent welded joint being a double sided shear joint.