H-F welding press for two three=dimensional films - welds them between electrodes positioned inside metal box and automatically earths screens to box when assembly enters it

摘要

A h/f welding press bonds films with electrodes of the required shape, one of them being moved to and from the material to be welded. To bond together at least two three-dimensional films with a dense seam a forming tool inside a box is shaped internally to the form of outer surface required in the welded product; the films are positioned accurately each side of the welding plane in the forming tool; the h/f electrode has a strip with at least a two-dimensional bend and is attached to a metal plate which matches the shape of the weld. This strip has a flat backing electrode which is also shaped to match the weld seam and which grips the edge of the films against the strip in a gap in the plane of the weld; the gap concerned can be reduced to a set degree by evacuating a space by the two metal plates before or while applying h/f, and this increases the penetration of the electrode strip into the films; a pressure tool is connected to the earthed outside conductor round the h/f cable and has a screen which meets the metal box when the metal plate plus strip enter the forming tool; at the same time the electrode strip on the metal plate plus the backing electrode are brought into the screened area. ADVANTAGE - The layout of the electrodes produces high grade three dimensional welds between films at reasonable cost.