Method of making a baffled waterbed

Abstract

To achieve maximum strength and reliability, a bag for use as a waterbed mattress is formed entirely of lap welds, that is, without any butt welds. My U.S. Pat. No. 3,825,172 discloses a lap weld method in which a length of plastic material is rolled to form a tube, the ends being lapped and partially welded to leave an access opening to the inside of the bag. The tube is telescoped over a welding die having the cross sectional configuration of the mattress, but axially short. The tube is accordion folded about the thin form with the ends of the tube turned inwardly over the peripheral rims of the form. End pieces are then welded in place. The form is removed through the access opening and the partial weld completed by the aid of a separator stick removable through the fill hole. To baffle the bag without changing the foregoing process, baffles are formed as a pair of detachably connectable elements respectively welded to the opposite sides of the tube that later will form the top and bottom layers of the mattress. The elements being detached from each other, fold with the tube along sides of the welding die. As a final assembly step, the baffle elements are connected together by simple manipulations through a later closed gap in the lap weld of the tube or by manipulations from the outside of the completed bag. The connected baffles operate to damp wave motion of fluid in the bag.