The method and the apparatus in question are intended in particular for folding of the vertical flaps P2 and P3 and importantly the flaps P3. For the folding of these flaps, the known art describes an apparatus and the associated operating method described in US patent No. 5,228, 273, according to which the rear flap P3 is folded with feeding of the packages one after another along a predetermined horizontal path and at a predetermined speed, so that the said packages are situated transversely with respect to the said path and arranged with the protruding parts M1 and M2 of the wrapping positioned on the sides of this said travel path along which respective yieldable or flexible folding members, usually consisting of brushes, are brought into co-operation at the rear with these protruding parts M1, M2, said folding members being displaced in the direction of feeding of the package so as to fold and flatten the said rear flaps P3 onto the ends of the product. The vertical and front flaps P2 are instead folded by fixed folding members underneath which the rear flaps P3 are also

inserted by means of the said brush folding members which keep these flaps folded onto the product until the moment of transfer underneath the fixed folding members.

This solution has the following drawbacks: the flexible or yieldable folding member, which is formed for example by a brush, does not ensure uniform flattening of the folded flap, so that the latter may have small wrinkles when it co-operates with the fixed folding member, with consequent irregular insertion or difficulty of insertion underneath this folding member. Even in the best flattened condition of the folded flap, transfer of the latter underneath the fixed folding member is always problematic and uncertain since the brush abandons the folded material at the same instant in which it meets the front rounded edge of the fixed folding member.

The invention intends to overcome the drawbacks of the known art, with the following solution. The front rounded edge of each fixed folding member is shaped with a comb-like form, with slits and with horizontal teeth, so that the movable folding member is able to still remain for a short time in contact with the folded flap, even after the latter has been inserted underneath the said fixed folding member, in this case underneath the leading teeth of this folding member. For its part, the movable folding member is designed with a form suitable for the abovementioned purpose and preferably consists of a pad of suitable rigid material able to prepare positively, without irregularities, the surface of the flap to be folded, and the surface of the pad which acts on the flap is characterized by a fretted vertical profile with longitudinal raised parts interspaced by longitudinal channels aligned with the teeth of the fixed folding member. When the movable folding member reaches the fixed folding member, the raised parts of the said movable folding member are inserted into the interdental openings of the fixed folding member and the teeth of the latter are inserted into the longitudinal channels of the said movable folding member which, before passing beyond the teeth of the fixed folding member, is moved away with suitable timing from the latter as a result of its curved travel movement around one of the driving ends of the associated movement conveyor.

Further features of the invention will appear clearly from the following description of a preferred embodiment illustrated in the figures of the accompanying

drawings, in which, in addition to Figures 1 and 2 already considered: - Fig. 3 shows a plan view of the apparatus with the pairs of movable folding members and fixed folding members and with the associated adjusting means for adaptation to packages of varying format; - Fig. 4 shows a perspective and inner side view of one of the movable folding members with the following fixed folding member; - Figs 5 and 6 show a top plan view, respectively, of the first step involving co- operation of the movable folding member with the flap to be folded and the last step during which the movable folding member abandons the folded flap, after the latter has been taken up by the fixed folding member.

In Figure 3,1 denotes the ideal horizontal plane along which the package M with the product R travels, resting thereon with a transverse arrangement, as already mentioned with reference to Figures 1 and 2 and on this plane the packaged product advances with the aid of means of known type, schematically indicated by the arrow 2. The ends M1 and M2 of the package, projecting from the ends of the product R, are situated projecting on the sides of the surface 1 so as to be able to co-operate in succession with the movable folding members A which fold the rear flaps P3, then with the fixed folding members B which keep the said rear flaps folded after they have been abandoned by the movable folding members and which fold the front flaps P2 and the bottom flaps P4, and finally with the facing conveyors C which perform heat-welding of the folded and superimposed flaps P1-P4 using the so-called hot- plugging method. When the package reaches the movable folding members A, the upper flap P1 has been already folded and is held by known guiding means which are not considered here. The movable folding members A comprise identical and positive conveyors 3,103, for example of the toothed-belt type, driven on pairs of vertical-axis pulleys 4,104 supported rotatably by respective frames 5,105, with the front toothed pulleys mounted statically on the said frames and connected to respective drive units 6,106 with encoders, which can be connected electrically and are of the type with an electronic speed and phase control motor, for example brushless motors, while the rear pulleys are mounted on the frames 5,105 idle and

with longitudinal displacement slides arranged in between, and adjusting means 7, 107 are envisaged for co-operation with these slides so as to allow the necessary tensioning of the belts of the conveyors 3,103 which, with the sections facing the surface 1, are parallel with the travel path of the package, travel in the same direction as the said package, with varying movement (see below) and are positioned close to the protruding end portions M1 and M2 of the package, without however interfering negatively with the latter.

The frames 5,105 of the conveyors 3,103 support, fixed at the top, transverse slides 8,108 which slide on the straight guiding lintel of a gantry structure 9 situated transversely with respect to the surface 1 and fixed with the uprights to the frame of the apparatus. Parallel to this structure 9, fixed end supports 10,110 rotatably support a double screw 11 with opposite and identical threads which co-operate with respective nut screws 12,112 fixed to the frames 5,105 of the conveyors 3,103 so that, by rotating this screw using end hand-wheels 13 or a servo-control system and using associated remote control devices (not shown), it is possible to adjust in a self- centring manner the relative distance between the said conveyors so as to adapt it to the format of the packages which are to be processed.

The length of the conveyors 3,103 is related to the different range of formats of the packages which the apparatus must process and usually two movable folding members which are equally spaced from each other are usually associated with the said conveyors so that, while a folding member follows a curved path around the driving pulley and abandons the package on which it has acted, a following folding member passes around the driven pulley and is ready to act on a following package which is to be closed. It is understood, however, that a number of movable folding members different from that indicated above may be associated with the conveyors 3,103. From Figure 4 it can be seen that the belts of the conveyors 3,103 have fixed thereto, along their vertical middle axis, supports 14, 114 which are arranged so that it is possible to fix, on their outer side surface, vertical descending flanges 15, 115 which carry on their bottom end the respective folding shoes 16,116 which are designed to be interchangeable upon variation in the format of the package to be

formed. Upon variation in the format of the package it is for example envisaged changing only the shoes 16,116, keeping unchanged their reference position with respect to the bottom end of the flanges 15,115 and consequently the surface 1 along which the packages travel. The shoes 16,116 are substantially parallelepiped shaped, with their outer vertical edges being suitably rounded, are made or lined with material having a low coefficient of friction vis-a-vis the packaging film M and their surface intended to come into contact with the film is characterized by a fretted vertical profile defined by longitudinal grooves spaced by longitudinal raised parts.

Between the package feeding means 2 and the conveyor assembly 3,103 another step is performed by special programming and control means (not shown) so that, when one of the said members 2 is about to reach the driven pulleys 4,104 of the said conveyors, a folding~ member~-1-6, 116-is-following a curved path around- these pulleys until it touches with its front edge the outside of the flap P3 of the package and in such a way as to start folding this flap onto the nearby ends of the product, as indicated in succession in broken and continuous lines in Figure 5. When the movable folding members 16,116 travel along the inner straight section of the respective conveyors 3,103 and proceed in the same direction as the package, the said folding members initially advance at a speed which is normally slightly greater than that of the said package, so as to flatten out the folded flap and act on its most advanced part, following which, via the said means for controlling the motors 6,106, the folding members 16,116 are made to advance at the same speed as the package. This initial acceleration of the folding member during the active stage does not negatively affect operation of the folding member upstream since the latter has already terminated its active cycle and is about to travel along the return section of the associated conveyor 3,103.

From Figures 3 and 4 it can be seen that the active components of the fixed folding members B consist of flat and straight plates 17, 117 arranged edgewise and with their inner surface substantially coplanar with the ends of the product R being packaged. At least the active surface of these components is for example Teflon- lined or otherwise treated for low-friction co-operation with the flaps of the package to

be folded. According to known solutions (Fig. 4), the plates 17,117 have an oblique longitudinal cut 18 which is open at one end on the bottom side of these components, at the correct distance from their front edge, and open at the other end on the rear vertical side of the said folding members, and this ascending cut has the function of receiving and folding upwards the bottom flap P4 of the packages, while the latter advance in contact with the folding members in question.

The composite plates 17,117 have a height which is related to the larger heightwise dimension of the packages to be closed and, by means of rear outer spacers 19,119 (Fig. 3), these plates are fixed to slides 20,120 which slide on horizontal guides 21,121 fixed to the said movable frames and adjustable using self- centring means-schematically indicated by the arrows 23,123-which carry the heat-welding ~end conveyors C situated with their active section coplanar with and immediately downstream of the plates 17,117. Upon a variation in the format of the packages, by operating the adjusting means 23,123, the operative position both of the conveyors C and of the fixed folding members B will vary simultaneously, while it will be possible to adjust the latter in an independent manner by means of fine adjusting means 24,124 acting between the slides 20,120 and the associated guides 21,121. From Figures 3 and 4 it can be seen that the front edge of the folding plates 17,117 has, fixed thereto, respective borders 25,125 made or lined with material having a low coefficient of friction when in contact with the film of the packages and having substantially the form of a scalene trapezium, with the larger base directed towards the said plates, with the smaller base at the bottom and with the longer oblique side at the top. The front edge of the said borders is suitably rounded and, over a section with a height corresponding to that of the maximum packaging format to be formed, starting from the smaller base and proceeding upwards, has slits 26,126 of suitable depth inside which the raised parts of the movable folding members 16,116 are able to engage. The bottom edge 1026 of the slits 26,126, as can be seen in Figure 6, is suitably chamfered, for example with a rounded form similar to that of the front edge of the borders 25,125. The face of the borders 25,125 directed towards the package is coplanar with the active surface of

the folding plates 17,117.

From Figure 6 it can be seen that, when the movable folding members 16,116 reach the end of the straight inner section of the associated conveyors 3,103, they partly enter with their reliefs into the slits 26,126 of the front edge of the fixed folding members, with the result of correctly keeping the folded flap P3 in contact with the end of the product and ensuring entry of this flap without the slightest interference underneath the front edge 25,125 of the fixed folding members 17,117, and with suitable timing, by means of the motors 6,106, the linear displacement of the movable folding members 16,116 is accelerated so that the part of them which remains in contact with the folded flap P3 and which lies substantially in an orbit Q concentric with the driving pulley of the conveyors 3,103 travels with a peripheral speed, the-component-of which parallel-to the-conveying component-of the means 2,-- is the same as or slightly greater than that of feeding of the packages, so as to keep the said folded flap P3 always correctly spread out, even during insertion underneath the fixed folding member. This acceleration of the conveyors 3,103 during disengagement of the movable folding members 16,116 from the ends of the package also does not negatively affect the correct operation of the movable folding members situated upstream since they are not yet in the active position, still abandoning the return section of the associated conveyors 3,103 and following a curved path around the driven pulleys. Obviously, before the rear flap P3, the front flaps P2 of the packages co-operate with the plates 17,117 of the fixed folding members and, by means of these plates, are correctly folded and spread out on the ends of the packaged product.

When the package leaves the plates 17,117 of the fixed folding members B, all four end flaps P1-P4 of the package have been folded onto the ends of the product such that, when they co-operate with the inner heated sections of the end conveyors C, the said flaps P1-P4 are fixed together by means of the usual heat- welding operation.