The present finding relates to the paper and cardboard industry and, more particularly, a container in the form of a bag whose peculiar feature is that, unlike all envelopes, bags or boxes available on the market, both its corners of the upper side of each face are cut along the diagonal of a square, a bellow being provided at each such corner forming the prolongation of the side bellows, however, unlike the latter, it operates to the horizontal direction or to an inclined direction with respect to the plane of such side bellows so that the faces of the bag are allowed to approach or to separate without protruding from the upper periphery of the bag. Thus, when a weight is placed into the bag, the edges of the bag are caused to close automatically without any need of manual operations.

A further advantageous feature of the finding consists in that such bag can be manufactured in the standard size by folding many times a punched sheet with only one side glue strip.

The invention also relates to a method of and means for manufacturing such shopping bag.

According to the invention, while the layout (that can be obtained by an ordinary socket punch) of the creasing lines of the lower bag portion provided with support material follows the conventional layout used for all of the commercial bags, the layout of the upper bag portion of the standard type is made, apart

from size, by means of a grid always consisting of forty-four squares, the side of which is equal to half horizontal length of the side bellow as it is fully open, to which the extension of trimmed borders, glue strips, and redundancies should be added.

As can be seen below, such upper layout is characterized by four isosceles right-angle triangles, the size of which is the same as the triangles of the lower bag portion defining, as known, the creasing lines of the side bellows, however, the hypotenuse of the former triangles is disposed vertically. An advantageous feature of the shopping bag disclosed is that while the length of its base is set by the above-mentioned grid so as to be equal to three times the base of the bellow, the height of the bag can be changed at will according to requirements and the goods to be stored as well the size of paper that should be used for its manufacturing.

The description of the finding will be more readily understood with reference to the accompanying drawings that show by way of a not limiting example some preferred embodiments thereof. In the drawings:

Fig. 1 is the layout of the creasing lines for the base design showing a grid at the upper bag portion with trimmed borders and redundancies;

Fig. 2 is a perspective view of the bag made by the layout of fig. 1;

Fig. 3 shows the layout of the creasing lines for a second design;

Fig. 4 shows the layout of the creasing lines for a third design;

Fig. 5 shows the layout of the creasing lines for a fourth design;

Figs. 6, 7 and 8 show the several manufacturing steps of the bag of fig. 2;

Figs. 9, 10, 11 and 12 show as many designs made from the same socket punch which differ in the handles and closure systems;

Fig. 13 shows another design made by the same socket punch and characterized by an outer flap formed by folding to the outside a portion of the upper edge.

With reference to figure 1, the layout of the creasing lines of the base design, apart from size, is obtained, at its upper portion, by using a grid formed of forty-four like squares distributed to three parallel rows of sixteen squares each, that take up the whole of the sheet except for glue strip 4, i.e. the portion for glue strip, as well as trimmed border and redundancies 6. Only thirty-six squares designated by QE of the above-

mentioned forty-four squares of the grid, the sides of which are half the base length of the bellow, are essential for forming the corners. The latter are obtained by using the diagonal of the squares . as explained below.

The base design can be modified according to size requirements by manipulating only the remaining twelve squares QV located at the centre of the base grid. The upper grid allows a pair of bellows indicated as a whole at SSl and SS2 in figs. 1 and 2 to be formed in addition to form the periphery of the faces having upper corners cut along the diagonal of a square. Such bellows springing from side bellows Sl and S2 are extendible by spreading apart a two-flap folding and cause the access opening to the bag to reduce by itself as soon as an object with a suitable weight is put into the bag.

All of creasing lines needed for the base design shown in fig. 2 will be explained into detail below. Such creasing lines are drawn in bold type in fig. 1 where both faces and bellows are designated by like references. The two faces are essentially formed by two like hexagons, the upper base ZH of which is connected to vertical sides WM and GN through two oblique sides WZ and HG, each of them corresponding to the diagonal of a square of the grid.

Point W of one face is instead connected to point G of the other face of the bag by creasing lines GP and WP which are oriented to the same direction and have the same size as the catheti of isosceles right-angle

triangle MON allowing, together with vertical creasing line OP2, side bellows Sl and S2 to be formed. With reference to such triangle MON, a feature of the finding is that all four isosceles right-angle triangles ZKY and HUT of both sides of the upper portion differ from the former only by the different orientation of the hypotenuse which is disposed vertically instead of horizontally. It should be appreciated that the only horizontal ' creasing line in the upper portion, indicated at 2, allows the first row of sguares to be folded to stiffen the upper edge of the bag.

Advantageously, the above-mentioned grid allows the outline of the creasing lines to be designed for different bags having the same construction features but with the only constraint that the number of sguares indicated at QE as well as their size with respect to the base width of the bellow is kept unchanged. Figs. 6-8 show the several manufacturing steps, of the bag of fig. 2 by the outline of fig. 1. In detail, the steps are as follows:

1) Folding "glue reserve" border 4 onto the sheet which could be of paper, cardboard or any other suitable material after being punched;

2) Trimming right side A as necessary, about Η cm;

3) Folding the sheet onto creasing line FM so that the two widths of the sheet correspond to each other;

4) Sticking the two portions; 5) Forming the side bellows by squaring folding the

sheet along vertical creasing lines IN and FM that limit the width of the bag and by folding to the inside the two halves of the sheet by means of creasing line P20, as shown in fig. 6; 6) Forming the bottom conventionally by interposing a base support, for instance a thin paperboard, as usual;

7) Folding to the inside the edge formed by the first row of squares along longitudinal creasing line 2 to form the upper edge, as shown in fig. 7;

8) Folding to the inside the upper ends of the side bellows to take the shape shown in fig. 8 along oblique creasing lines HT and vertical creasing lines HU, GI and WF so that the bag can take the peculiar shape of the two faces provided with diagonally cut upper corners;

9) Folding to the inside the edge between creasing lines YT and ZH along line ZH.

The base design of fig. 2 only needing a drill to bore holes for string 40 is thus formed.

With reference still to fig. 2, the bag can be made of only one sheet with only one side glue strip. The operator is, however, free to couple two sheets with two side glue strips especially for larger size bags. The several designs shown in figs. 9, 10, 11 and 12 are all made by using one sheet and the same socket punch used for the base design of fig. 2 but by only modifying the manual fitting. In particular, the bag shown in fig. 9 is made without folding the edge to the inside along line IN by

inserting a support paperboard and forming a socket punch for handle 42.

Fig. 10 shows the same bag as fig. 2 where the handle is replaced by a string 44 or the like. The designs of figs. 11 and 12 show several types of fittings by providing adhesive closure plugs 46 or tapes.

Fig. 13 shows a variation of the bag of fig. 2 where the closure is obtained by an outer flap fastened by a tape 48. The flap is provided upon fitting by folding to the outside the edge between creasing lines YT and

ZH along line ZH.

The layouts of the creasing lines of figs 3, 4 show that the horizontal dimension of the bag' s face can be varied by decreasing or increasing the number of squares QV of the central portion.

Fig. 5 shows a variation where the first row of upper squares is missing. The number of squares is reduced to thirty-two by trimming the punched sheet. Thus, even if the faces of the bag have the same upper shape as the preceding design, upper bellows Sl and S2 allowing the bag to be closed automatically upon- putting a weight into it are missing.