Abstract: A stress free baffled waterbed mattress bag consists of an array of individual baffles, each of the baffles comprising a plurality of vertically stacked bladders serially connected, the end bladders being respectively attached to the operative top and bottom mattress bag layers. Each of the bladders comprises a pair of circular layers peripherally welded together and centrally attached respectively to the corresponding layer of the companion bladder and the top or bottom operative mattress layer.

Abstract: Two rectangular pieces of plastic material corresponding to the top and bottom layers of the bag to be formed are placed end to end and looped to form a tube. The overlapped ends are partially welded together to leave long access slits to the tube. The incompletely formed tube is telescoped over a welding die having the same general configuration of the tube, but axially compressed. The edges of the tube openings are turned inwardly over the generally rectangular rims at opposite ends of the die. The corners of the rims are rounded so that the inwardly turned edges form a one layer continuous flange free of wrinkles. Rectangular end pieces are then lap welded to the flange. The incompletely formed waterbed mattress is removed from the die. Individual baffle structures are welded to the top and bottom layers of the bag by secondary operations in which a jig mounting a row of baffle structures projects through the tube slits to position the baffle structures during a welding operation.