METHOD OF MAKING A PIECE OF TUBE FROM A FLAT WEB OF FLEXIBLE MATERIAL, AND APPARATUS FOR CARRYING OUT THE METHOD

摘要

A method of and apparatus for forming tubular containers from a flat web of flexible material such as paper coated with plastics are described. Two longitudinally extending grooved lines are formed on the web and spaced incisions are made extending laterally from the longitudinal edges of the web to the grooved lines. The incisions enable side portions to be folded about the grooved lines. The two side portions are curved and overlap at their edges and the intervening portion remains flat. The overlapping edges form a seam which is welded in a subsequent stage. The final shape of the container is achieved in a later stage. An advantage of the invention is that virtually no forces tending to destroy the weld come into play immediately after the weld is formed and this enables a simple and short welding step and short cooling period to be used. The method is, therefore, simplified and speeded up.