GB864826A - Improvements in and relating to tetrahedral containers and the manufacture thereof - Google Patents

Abstract

864,826. Tetrahedral packages. BERGLUND, E. E. June 9, 1959 [June 10, 1958], No. 19710/59. Class 94(1). To minimize surface defects on tetrahedronshaped packages made from web material, all necessary handling of the web or the tube formed therefrom which involves a risk of damage is carried out in those zones of the web or tube which, at the moment of sealing, are located within the sealing surface and so do not affect the actual tetrahedron surfaces of the finished packages. The tube is also pre-creased along the zones to be sealed such that when the precreased area is sealed any damage due to the pre-creasing is contained within the sealed area. In Fig. 5, narrow edged jaws 3 close on the tube to form a sharp fold thereacross, and thereafter heat-sealing members 4 close on the tube and rack to the positions shown in broken lines to form an enlarged sealed area. In an alternative construction the members 3, 4 comprise single units on each side of the tube that are first closed on the tube to pre-crease it and are then rocked up and down to form an enlarged sealed area. The members 3 may then be used to sever the package. In Fig. 8 the sealing members house spring loaded creasing members; additional spring loaded members 6 serve to initially reduce the volume of the tetrahedron to allow for subsequent expansion of the contents when sealing is effected. In Fig. 9 heat-sealing rollers close on the filled tube and then roll up and down to widen the sealed area. Fig. 13 shows tetrahedron-shaped containers being made from a roll of paper and a reciprocating piston 5, synchronised with the heat-sealing members, contains a one-way valve such that on its down stroke the valve is open but on its upstroke the valve closes and the piston then tends to reduce the effective liquid head in the package being sealed. In Fig. 14 metal foil is coiled into tubular form before being creased and formed into tetrahedron shaped containers. After a flat sealing zone has been formed, the sealing zone may be severed and the cut edge folded over. A sealing strip may be added. In Fig. 19, rollers 14 and 15, synchronized with the heat sealing means (not shown), pre-crease the tube, and further shaping means 17, 16 also act on the tube before heatsealing is finally effected. Specifications 711,855 and 716,733 are referred to.