EP0297334A2

EP0297334A2 - Machine for the manufacture of containers produced with a sheet of foldable material such as cardboard, wood and the like

Info

Publication number: EP0297334A2
Application number: EP88109365A
Authority: EP
Inventors: Bruno Corali
Original assignee: Individual
Current assignee: Individual
Priority date: 1987-07-01
Filing date: 1988-06-13
Publication date: 1989-01-04
Anticipated expiration: 2008-06-13
Also published as: EP0297334A3; IT8721144A0; IT1221926B; EP0297334B1; DE3871623D1

Abstract

The present invention relates to a machine for the manufacture of containers produced with a sheet of foldable material such as cardboard, wood and the like. The machine (1) comprises: conveyor means (2) which move the sheets through a punching station (4), means (5) for positioning the sheets exiting from the punching station (4) on a folding die (6), so that the latter contacts a central region of the punched sheet corresponding to the bottom of the container to be produced, and folding means (7) which contact in sequence peripheral portions of the punched sheet which constitute the lateral faces of the container to be produced. Said folding means (7) move the peripheral portions of the sheet to fold around the folding die (6). The machine (1) furthermore comprises stapling means (8) which act on parts of the portions of the sheet folded and mutually superimposed to obtain the assembly of the container.

Description

The present invention relates to a machine for the manufacture of containers produced with a sheet of foldable material, such as cardboard, wood and the like, in particular for the production of biodegradable containers for small-size food products.
As is known, small-size food products, such as for example fruit, are very often packaged in basket-like containers of low-thickness synthetic material, which have a very low cost since they are produced by molding with plant having very high productivity.
The diffusion of these containers, due to their low production cost, has, however, given rise to serious problems as to their elimination after use, since the material employed for their production is practically not biodegradable.
On the other hand, the wood containers used before the onset of synthetic containers entailed raw material costs and, even more, production costs such as to be extremely inconvenient.
The aim of the present invention is to provide a machine for the manufacture of containers produced with a sheet of foldable material such as cardboard, wood and the like, which has high productivity so as to significantly reduce the production cost of said containers to provide an incentive to their use.
Within this aim, an object of the invention is to provide a machine which can use reduced-thickness sheets without compromising the integrity of the container during the assembly step.
Another object of the invention is to provide a machine which has high reliability in operation and which requires reduced maintenance interventions.
Not least object of the invention is to provide a machine which requires a very limited number of operators so as to considerably contain the production costs of the containers.
This aim, as well as these and other objects which will become apparent hereinafter, are achieved by a machine for the manufacture of containers produced with a sheet of foldable material such as cardboard, wood and the like, characterized in that it comprises: means for conveying sheets through a punching station, means for positioning the sheets exiting from said punching station on at least one folding die, supporting in each instance a central portion of one of said sheets constituting the bottom of the container to be produced, folding means contacting in sequence portions of the sheet located around said central region of the sheet and constituting the lateral faces of the container to be produced, said folding means moving said portions of the sheet to fold around said folding die, stapling means being provided acting on mutually superimposed parts of said portions of the sheet folded for the assembly of the container.
Further characteristics and advantages of the invention will become apparent from the description of a preferred but not exclusive embodiment of a machine according to the invention, illustrated only by way of non-limitative example in the accompanying drawings, wherein:

figure 1 is a schematic lateral elevation view, in partial cross section, of the machine according to the invention;
figure 2 is a schematic top plan view of the machine according to the invention, with the folding means removed;
figure 3 is a front elevation view of the machine as viewed from the side of the folding means;
figure 4 is a lateral elevation view of a detail of the stapling means according to the invention;
figure 5 is a perspective view of the elements which control the actuation of the folding means;
figures 6 to 9 are schematic lateral elevation views, in partial cross section, illustrating the operation of the folding die and of the folding means;
figure 10 is a perspective view of the folding die according to the invention;
figure 11 is a sectional view of a detail of figure 2 taken along the axis XI-XI;
figure 12 is a sectional view of a detail of figure 2 taken along the axis XII-XII;
figure 13 is a partially sectional lateral elevation view of ejector means for the removal of the assembled container from the folding die;
figure 14 is a perspective view of a detail of the conveyor means according to the invention;
figure 15 is a lateral elevation view of a detail of the positioning means according to the invention; and
figure 16 is a perspective view of a container obtained with the machine according to the invention.

With reference to the above described figures, the machine according to the invention, generally indicated by the reference numeral 1, allows to produce containers of the type shown, only by way of example, in figure 16 and indicated by the reference numeral 100, which has a substantially rectangular bottom 101 and four lateral faces, of which two first lateral faces 102 and 103 are counterposed and two second lateral faces 104 and 105 are counterposed. The lateral faces are configured so that the container widens in the direction of its open side to facilitate stacking and the two second lateral faces 104 and 105 have flaps 106, 107, 108 and 109 which are superimposed in pairs on the outer side of the two first lateral faces 102 and 103 and rigidly associated therewith by means of staples 110.
The machine according to the invention comprises: conveyor means 2 which convey the sheets 3, deposited thereon, through a punching station 4, positioning means 5 which take the punched sheets from the conveyor means and deposit them in sequence on a folding die 6 so that the latter supports a central portion of the sheet which will constitute the bottom 101 of the container 100. Proximate to the folding die 6 there are provided folding means 7 which act on peripheral portions of the sheet, which constitute the lateral faces of the container, so as to fold them around the folding die, and stapling means 8 which apply the staples 110 to obtain the assembly of the container.
More particularly, the conveyor means 2 are constituted by a conveyor with a pair of chains 9a and 9b, parallel to one another, which extend laterally on opposite sides with respect to a horizontal rest plane 10 on which the sheets 3 are deposited. Each of the chains 9a and 9b is entrained by two toothed wheels 11a and 12a, 11b and 12b placed proximate to the longitudinal ends of the rest plane 10. To the chains 9a and 9b there are coupled, at regular length intervals, support frames 13 which extend transversely with respect to the extension of the chains 9a and 9b, i.e., transversely with respect to the direction of advancement 14 of the conveyor means. The chains 9a and 9b are actuated with an intermittent advancement as will become apparent hereinafter.
The support frames 13 have a base plate 15 which is rested on the rest plane 10 and is intended to be inserted below the sheet 3. On this base plate 15 shoulders 16a and 16b are provided which are intended to contact an edge of the sheet 3 to push it along the direction of advancement 14. Advantageously, the conveyor means 2 comprise grip means 17 which are controllably engageable with the sheets 3 to convey them in a precise manner along the rest plane 10.
Said grip means 17 are constituted by a small plate 18 arranged above the base plate 15 and fixed at one of its ends transversely with respect to a shaft 19 which is arranged perpendicular to the direction of advancement 14 and is supported oscillably about its axis by the support frame 13. Proximate to a lateral edge of the rest plane 10, the shaft 19 is provided with a transverse arm 20 which is engageable with a control profile 21 which extends parallel to the chains 9a and 9b up to the proximity of the positioning means 5. The engagement of the transverse arm 20 with the control profile 21 causes the oscillation of the shaft 19 about its own axis with consequent engagement of the small plate 18 with the edge of the sheet 3 which is gripped between the free end of the small plate 18 and the base plate 15. The oscillation of the shaft 19 due to the approach of the small plate 18 to the base plate 15 is opposed by a return spring 22, wound about the shaft 19, which causes the lifting of the plate 18 from the base plate 15 when the engagement between the transverse arm 20 and the control profile 21 ceases.
On the rest plane 10 there may be provided a shoulder 23 which extends parallel to the direction of advancement 14 and which is adjustable in a direction transverse thereto according to the dimensions of the sheet 3 to obtain its correct positioning before it is locked by the small plate 18.
The punching station 4 is constituted by a press 24, of a known type, actuated with reciprocating back and forth motion in a direction perpendicular to the rest plane 10 by means of an eccentric 25. The press 24 is downwardly provided with a punch 26 which faces a counterpunch 26a accommodated in the rest plane 10 and which cuts and presets folding lines on the sheet 3 according to a preset shaping to obtain the container 100.
Upstream of the punching station 4, following the direction of advancement 14, there may be provided an element 27 for detecting the presence of the sheet 3, for example a photocell, which interrupts, in a known manner, the actuation of the press 24 in the absence of sheets 3. After the punching station 4, along the direction of advancement 14, there is provided a cleaning element 28 for removing punching residues from the sheets 3. Said cleaning element 28 is constituted by a plate 29 facing the rest plane 10 and controllably movable towards or away from a counterplate 30 accommodated in the rest plane 10. The counterplate 30, which receives the sheet 3 exiting from the punching station 4, has a configuration identical to the exact configuration of the sheet already punched to obtain the container 100, while the plate 29 is downwardly provided with protrusions shaped like the edge of the punched sheet so as to obtain the removal of any burr which is not completely removed with the punching action. To obtain the actuation of the cleaning element 28 it is sufficient to rigidly connect the plate 29, by means of an appropriate arm 31, to the press 24 of the punching station 4 so as to obtain the cleaning of an already punched sheet while the punching station 4 is punching the immediately successive sheet.
Furthermore, downstream of the cleaning element 28, between the latter and the positioning means 5, auxiliary stapling means 32 are arranged for the application on the punched sheets 3 of reinforcement staples. The auxiliary stapling means are conveniently used, if the sheet 3 is made of wood, to apply staples 111 astride those folding lines, obtained with the punching, which are parallel to the fibers of the wood so as to avoid the detachment of pieces of sheet in the subsequent folding operation. The auxiliary stapling means 32 are constituted by stapling heads 33, for example of the type described in the patent No. 837070, filed on 6.28.1968 by the same Applicant, which face riveting elements 34, also of a known type, arranged on the rest plane 10.
The positioning means 5 comprise a pneumatic grip element 35 which is controllably engaged by negative pressure with the upper face of the incoming sheet 3 and which is controllably movable along the direction of advancement 14 to move the sheet 3 onto the folding die 6.
More particularly, the pneumatic grip element 35 is constituted by a pair of arms 36a and 36b which are mutually spaced apart transversely with respect to the direction of advancement 14 and which are internally hollow. The two arms 36a and 36b face the rest plane 10 with openings 37a and 37b which are connected, by means of flexible tubes 38a and 38b, to an aspiration device 39 supported by the support structure 40 of the machine in an upper region.
The two arms 36a and 36b are fixed to a carriage 41 which is movable with reciprocating motion along guides 42a and 42b which extend on opposite sides laterally to the rest plane 10 in raised position.
More particularly, the carriage 41 is constituted by a frame which is arranged transversely with respect to the direction of advancement 14 and which rests with wheels 43 on the guides 42a and 42b fixed to the support structure and arranged parallel to the direction of advancement.
The two arms 36a and 36b may furthermore have abutments 44a and 44b for the correct grip of the sheet 3; said abutments 44a and 44b are adjustable parallel to the direction of advancement of the sheet according to the dimensions of the sheet. The elements which cause the alternate movement of the carriage 41 along the direction of advancement are described hereinafter.
The folding die 6 substantially reproduces the inner configuration of the container 100 and is arranged with the portion 6a, which reproduces the bottom 101 of the container, directed upwards. The folding die 6 is furthermore laterally provided with portions 6b and 6c which correspond to the two first lateral faces 102 and 103 of the container to be produced and with portions 6d and 6e which correspond to the two second lateral faces 104 and 105 of the container.
Advantageously, four folding dies 6 are provided, identical to one another, which are mounted on the free ends of four spokes 45, mutually angularly offset by 90°, of a wheel 46 arranged with its axis transversely with respect to the direction of advancement 14. The wheel 46 is actuated, as will become apparent hereinafter, with intermittent rotary motion about its axis so as to sequentially move the dies 6 below the folding means 7 with the portion 6a arranged substantially at the same level of the rest plane 10 in a position adapted to receive the sheet which is deposited thereon by the positioning means 5 and successively in a container unloading position.
Above the folding die which is located in this position there are arranged the folding means 7 which comprise a first folding plate 47, which is arranged above and parallel to the portion 6a of the folding die and which has a configuration corresponding to the bottom 101 of the container, in this case rectangular, with a pair of downwardly folded wings 48a and 48b, on two counterposed sides. The first folding plate 47 is controllably movable towards or away from the portion 6a of the folding die so as to interfere with peripheral portions of the sheet which constitute the two first lateral faces 102 and 103 of the container to be produced to move them against the portions 6b and 6c of the folding die.
The folding means also comprise a second folding plate 49 which is arranged upwardly and parallel to the first folding plate 47 and is configured similarly thereto with the difference that it has a pair of wings 50a and 50b angularly offset with respect to the wings 48a and 48b, i.e., arranged on the other two counterposed sides of the rectangular configuration corresponding to the bottom 101 of the container. The second folding plate 49 is also controllably movable towards or away from the folding die 6 so as to interfere with the portions of the sheet which constitute the two second lateral faces 104 and 105 of the container and to fold them on the portions 6d and 6e of the folding die 6.
Downwardly with respect to the first folding plate 47, locking means are provided which keep the sheet 3 in place on the folding die during the action of the folding means. Said locking means are constituted by a third plate 51 which is arranged below and parallel to the first folding plate 47. The third plate 51 has smaller dimensions than the plate 47 and is slideably associated therewith along a direction perpendicular to the arrangement of the portion 6a of the folding die on which the sheet 3 is arranged. More particularly, the third plate is supported by pins 52 axially slideable in holes 53 defined in the first folding plate 47; on the pins 52 there act springs 54 which push them downwards so that the lowering of the first folding plate 47 causes the resting of the third plate 51 on the sheet rested on the portion 6a of the folding die and so that the first folding plate, which contacts the sheet with the wings 50a and 50b, after the locking of the sheet, may continue its descent against the biasing action of the springs 54, which in the successive step of lifting of the first folding plate 47, when the folding has ended, again move away the third plate 51 thereunder.
The folding means 7 furthermore comprise two lateral arms 55, 56 which face the counterposed lateral portions 6d and 6e of the folding die 6 and which are provided with end portions 55a and 56a which reproduce the two second lateral faces 104 and 105 of the container 100 to be produced and part of the two first lateral faces 102 and 103. The arms 55 and 56 are controllably movable with the end portions 55a and 56a towards or away from the folding die 6 to contact the flaps 106, 107, 108, 109 of the two second lateral faces 104 and 105 and fold them in sequence on the already folded first two lateral faces 102 and 103 of the container 100.
The two arms 55 and 56 are pivoted at one of their end portions, opposite to the portions 55a and 56a, to a support 57 fixed to the support structure 40 of the machine on which there are also slideably mounted in a direction perpendicular to the rest plane 10, the first folding plate 47 and the second folding plate 49. The two arms 55 and 56 are individually controllably oscillable about their fulcrum in a vertical plane to move their end portions 55a and 56a to contact the portions of the sheet to be folded around the folding die 6.
More particularly, to control the folding means, four cams 58, 59, 60 and 61 are provided which are mounted on a same shaft 62 arranged transversely with respect to the direction of advancement 14 and supported rotatably by the support structure 40 of the machine. Each cam has an actuation region, respectively 58a, 59a, 60a and 61a which acts on levers 63, 64, 65, 66 connected to the folding means. The levers 63, 64, 65 and 66 have one of their ends pivoted to the support structure and the other end pivoted to a vertical rod, respectively 67, 68, 69 and 70, which acts respectively on the first folding plate 47, on the second folding plate 49 and on the arms 55 and 56 to obtain their movement towards or away from the folding die 6, as already described, by the action of the cams 58, 59, 60 and 61 which act on an intermediate portion of the levers 63, 64, 65 and 66. To maintain contact between the levers 63, 64, 65 and 66 and the cams, elastic means are provided which are constituted by four pneumatic pistons 71 each whereof acts on one of the levers 63, 64, 65 and 66 and is fed by means of an appropriate compressed-air accumulator 72 associated with the support structure 40 of the machine. Furthermore, the initial portions of the actuation regions 58a, 59a, 60a and 61a of the cams are angularly offset with respect to one another so that the levers 63, 64, 65 and 66 act in sequence on the folding means.
The stapling means 8 are constituted by stapling heads 73 which are arranged facing the lateral portions 6b and 6c of the folding die 6 and are provided with riveting elements 74 rigidly associated therewith. Said stapling heads 73, fully similar to the stapling heads 33 except for the riveting elements 74, are controllably movable from below upwards to move the riveting elements 74 onto the inner surface of the two counterposed first lateral faces 102, 103 of the container 100 on the folding die 6 and to staple the flaps 106, 107, 108 and 109 to the first two lateral faces 102, 103 of the container 100.
Advantageously, to facilitate the insertion of the riveting elements 74 on the inner side of the two first lateral faces 102, 103 of the container, the portions 6b and 6c of the folding die 6 have appropriate downwardly open missing portions 75b and 75c.
To obtain the movement from below upwards of the stapling heads 73 it is possible to provide said stapling heads 73 hinged to a support element 76 so that they can oscillate in a vertical plane arranged transversely with respect to the direction of advancement 14, by the action of rods 77 connected to a crank 78, actuated by cams 112, or to an equivalent mechanical system synchronized with the folding means to intervene immediately thereafter.
Furthermore the amplitude of the oscillation of the stapling heads and their spacing from the folding die 6 may be adjusted in a known manner according to the dimensions of the container to be produced.
The machine according to the invention also comprises ejector means 79 which act on the container 100, assembled and moved from one of the folding dies 6 to the unloading position to obtain the disengagement of the container 100 from the related folding die.
Said ejector means 79 are constituted by a fork-like element 80 which is arranged with its two arms 80a and 80b laterally on opposite sides with respect to the folding die 6 in unloading position and is controllably movable radially with respect to the wheel 46 to interfere with the assembled container 100 and disengage it from the folding die 6.
More particularly, the fork-like element 80 is carried by a carriage 81 which is mounted with wheels 82 on a guide 83 which extends parallel to the direction of advancement 14. On the carriage 81 there acts a connecting rod 84-crank 85 assembly, actuated synchronously with the other elements of the machine to intervene after the folding die 6 has been moved to the unloading position with the rotation of the wheel 46.
For the actuation of many of the described elements of the machine one may use control means which comprise a main reducer assembly 86 which, by means of a chain 87, is connected to a main shaft 88.
The main shaft 88 is connected, by means of a chain 89, to the input shaft of a first intermitter 90, of a known type, which is connected with its output shaft, by means of another chain 91, to a pair of wheels 12a, 12b of the conveyor means 2 to obtain their intermittent advancement motion.
The main shaft 88 is furthermore connected by means of a chain 92 to the input shaft of a second intermitter 93, also of a known type, which actuates with intermittent rotary motion the wheel 46, with the folding dies 6, about its axis.
The main shaft 88 is also connected, by means of another chain 94, to the input shaft of a first oscillator 95, of a known type, which controls with its output shaft an oscillable lever 96 hinged to the carriage 41 of the positioning means 5, so as to obtain the reciprocating motion of the carriage 41 along the direction of advancement 14 as already described.
The main shaft 88 is furthermore connected, by means of another chain 97, to a second oscillator 98 which controls the connecting rod 84-crank 85 assembly for the actuation of the fork-like element 80 of the ejector means 79.
The main shaft 88 is also connected, by means of another chain 99, to the shaft 62 of the cams which control the folding means 7. The cams 112 which control the lifting or the lowering of the stapling means 8 may be keyed directly onto the shaft 62.
In this manner the conveyor means 2, the positioning means 5, the folding means 7, the stapling means 8, the ejector means 79, and the wheel 46 which carries the folding dies 6 are operatively connected to one another.
The operation of the machine according to the invention is as follows.
The sheets 3 are fed manually, or by means of a conveyor belt, on the rest plane 10. The conveyor means 2, by means of the grip means 17, convey the sheets 3 through the punching station 4 and through the cleaning element 28. To the punched sheets 3 there are applied the reinforcement staples 111 by means of the auxiliary stapling means 32 and said sheets are successively released by the grip means 17. The sheets 3, free from the grip means 17, are gripped one at a time by the positioning means 5 and arranged on the folding die 6 positioned with its portion 6a upwards. At this point the folding means 7 are actuated which in sequence provide the folding over the folding die 6 of the portions of the sheet 3 which constitute the two first lateral faces 102, 103 of the container and the two second lateral faces 104 and 105 of the container. The successive actuation of the arms 55 and 56 obtains the folding of the tabs 106, 107, 108 and 109 on the two previously folded first lateral faces 102 and 103 of the container. Once the folding has been performed, the stapling means 8 are actuated and complete the assembly of the container 100. Once the stapling has ended, the wheel 46 is rotated partially so as to move the folding die 6 in unloading position to allow the ejector means 79 to disengage the already assembled container 100 from the folding die 6. After the wheel 46 there may be arranged an upward slide, so that the ejector means 79 simultaneously provide the stacking of the containers 100, disengaged from the folding die 6, on said slide.
In practice it has been observed that the machine according to the invention fully achieves the intended aim and objects since, by virtue of the complete automation of the process of assembly of the containers, it has high productions which allow to considerably contain the unit cost of the containers even if produced in biodegradable material such as wood, cardboard and the like.
The machine thus conceived is susceptible to numerous modifications and variations, all within the scope of the inventive concept; moreover all the details may be replaced with technically equivalent elements.
In practice, the materials employed, as well as the dimensions, may be any according to the requirements and to the state of the art.
Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, such reference signs do not have any limiting effect on the scope of each element identified by way of example by such reference signs.

Claims

1. Machine for the manufacture of containers produced with a sheet of foldable material such as cardboard, wood and the like, characterized in that it comprises: means (2) for conveying sheets (3) through a punching station (4), means (5) for positioning the sheets (3) exiting from said punching station (4) on at least one folding die (6), supporting in each instance a central portion of one of said sheets (3) constituting the bottom (101) of the container (100) to be produced, folding means (7) contacting in sequence portions of the sheet (3) located around said central region of the sheet (3) and constituting the lateral faces (102,103,104,105) of the container (100) to be produced, said folding means (7) moving said portions of the sheet (3) around said folding die (6), stapling means (8) being provided acting on mutually superimposed parts of said portions of the sheet (3) folded for the assembly of the container (100).

2. Machine, according to claim 1, characterized in that said folding die (6) substantially reproduces the inner configuration of the container (100) to be produced and is arranged with its portion (6a) reproducing the bottom (101) of the container (100) directed upwards.

3. Machine, according to claims 1 and 2, characterized in that said folding means (7) comprise a first folding plate (47) arranged upwardly and parallel to the portion (6a) of the folding die (6) reproducing the bottom (101) of the container (100), said first folding plate (47) being laterally provided with two downwardly folded wings (48a,48b), said first folding plate (47) being controllably movable towards or away from said folding die (6) to fold two first ones of said portions of the sheet (3) constituting two first counterposed lateral faces (102,103) of the container (100) to be produced.

4. Machine, according to one or more of the preceding claims, characterized in that said folding means (7) comprise a second folding plate (49) arranged upwardly and parallel to said first folding plate (47), said second folding plate (49) being laterally provided with two wings (50a,50b), angularly offset with respect to the wings (48a,48b) of said first folding plate (47), and being controllably movable towards or away from said folding die (6) to fold two second ones of said portions of the sheet (3) constituting two second counterposed lateral faces (104,105) of the container to be produced.

5. Machine, according to one or more of the preceding claims, characterized in that it comprises means (51) for locking said sheet on said folding die.

6. Machine, according to one or more of the preceding claims, characterized in that said locking means (51) comprise a third plate (51) arranged below and parallel to said first folding plate (47), said third plate (51) being slideably associated with said first folding plate (47) along the direction of actuation of said first folding plate (47) to contact said sheet (3), located on said folding die (6), before the action of said first folding plate (47).

7. Machine, according to one or more of the preceding claims, characterized in that said folding means (7) comprise two lateral arms (55,56) facing the lateral portions (6d,6e) of said folding die (6) reproducing said two second counterposed lateral faces (104,105) of the container (100) to be produced, said two lateral arms (55,56) being shaped and controllably movable towards or away from said folding die (6) to contact and fold, on said two first counterposed lateral faces (102,103) of the container (100), flaps (106,107,108,109) of said two second counterposed lateral faces (104,105) of the container (100).

8. Machine, according to one or more of the preceding claims, characterized in that said first folding plate (47), said second folding plate (49) and said two lateral arms (55,56) are actuated towards or away from said folding die (6) by means of four cams (58,59,60,61) mounted on a same shaft (62) actuated with rotary motion about its own axis, said cams (58,59,60,61) having actuation regions (58a,59a,60a,61a) operatively connected respectively to said first folding plate (47), to said second folding plate (49) and to said two lateral arms (55,56), the initial portions of said actuation regions (58a,59a,60a,61a) being angularly offset with respect to one another for the sequential actuation of the folding means (7).

9. Machine, according to one or more of the preceding claims, characterized in that it comprises a plurality of folding dies (6) movable in sequence below said folding means (7) in a position adapted to receive a sheet (3) to be folded and in an unloading position of the assembled container (100).

10. Machine, according to one or more of the preceding claims, characterized in that said stapling means (8) comprise stapling heads (73) for the application of staples (110), provided with riveting elements (74), said stapling heads (73) facing the lateral faces (6b,6c) of said folding dies corresponding to said two first counterposed lateral faces (102,103) of the container (100) and being controllably movable from below upwards to move said riveting elements (74) on the inner surface of said two first counterposed lateral faces (102,103) of the container (100) on said folding die (6).

11. Machine, according to one or more of the preceding claims, characterized in that said folding die (6) has, on its two faces (6b,6c) corresponding to said two first counterposed lateral faces (102,103) of the container (100), missing portions (75a,75b) to allow the insertion of the riveting elements (74) moved to said stapling heads (73).

12. Machine, according to one or more of the preceding claims, characterized in that it comprises ejector means (79) acting on the assembled container (100) moved by one of said folding dies (6) into said unloading position for the disengagement of the container (100) from the related folding die (6).

13. Machine, according to one or more of the preceding claims, characterized in that said folding dies (6) are carried by the spokes (45) of a wheel (46) substantially tangent to the direction of advancement (14) of said conveyor means (2), said wheel (46) being actuated with intermittent rotary motion about its axis, arranged transversely with respect to said direction of advancement (14), to move each of said folding dies (6) in said position adapted to receive a sheet (3) arriving from said conveyor means (2) and successively in said position of unloading of the assembled container (100).

14. Machine, according to one or more of the preceding claims, characterized in that said ejector means (79) comprise a fork-like element (80) arranged with its two arms (80a,80b) laterally on opposite sides of one of said folding dies (6) in an unloading position, said fork-like element (80) being controllably movable radially with respect to said wheel (46) to interfere with said container (100) and disengage it from said folding die (6).

15. Machine, according to one or more of the preceding claims, characterized in that said conveyor means (2) are constituted by a chain conveyor (9a,9b) movable along a substantially horizontal rest plane (10) of said sheets (3).

16. Machine, according to one or more of the preceding claims, characterized in that said conveyor means (2) comprise grip means (17) controllably engageable with said sheets (3) for their conveyance on said rest plane (10) along a direction of advancement (14).

17. Machine, according to one or more of the preceding claims, characterized in that said positioning means (5) comprise a pneumatic grip element (35) controllably engageable by negative pressure with the upper face of a sheet (3) arriving from said punching station (4) and controllably movable along said direction of advancement (14) to move the sheet (3) onto said folding die (6).

18. Machine, according to one or more of the preceding claims, characterized in that between said punching station (4) and said positioning means (5) auxiliary stapling means (32) are provided for the application of staples (111) on the sheets (3) in regions to be reinforced.

19. Machine, according to one or more of the preceding claims, characterized in that it comprises, downstream of said punching station (4), according to said direction of advancement (14), a cleaning element (28) for the removal of the residues of the punching from the sheets (3).

20. Machine, according to one or more of the preceding claims, characterized in that said conveyor means (2), said positioning means (5), said folding means (7), said stapling means (8), said ejector means (79) are operatively mutually connected.