Packaging machine for forming envelopes

Abstract

 A packaging machine for forming envelopes is described of the type comprising an internal layer, made of a flexible film realized with a plastic thermo-weldable material, and an external wrapping (S), made of a rigid sheet material, constrainable to such an internal layer. The packaging machine (10) comprises a feeding unit (20) of the flexible film, a loading unit (12) of the rigid sheet material (S), a substantially vertical forming cylinder (24), around which the flexible film wraps up to assume a tubular shape, a first vertical welding unit, able to close vertically the flexible film tube, and a second horizontal welding unit (32), able to close in its lower part the flexible film tube and to cut its lower closed portion, so as to form an internal container for the envelope (P) welded on the lower side and open on the upper side. The packaging machine (10) also comprises an applying and overturning unit (36) that is able to take out each sheet (S) of rigid material, arriving at a spread position from the loading unit (12), and to overturn it according to an angle of approximately 90° to apply it around the internal container of the envelope (P).

Description

[0001] The present invention refers to a packaging machine for forming envelopes, in particular envelopes made up of a rigid wrapping to which a coating of flexible thermoplastic material is internally applied.

[0002] Packaging machines are known that are intended to form and fill envelopes, from a film made from flexible thermoplastic material, in which the product is introduced by falling vertically. Such machines are in fact named "vertical packaging machines".

[0003] Vertical packaging machines foresee the presence of a forming cylinder around which the flexible film wraps up so as to form a tube of film. The tube is then completed thanks to thermo-welding, in a vertical direction, of the outer edges of film that are placed over one another and are joined by effect of the welding. Slightly before the tube has been formed, the film must pass from the flat and tight state to the tubular shape: in order for this to happen, the film is rested on a curved surface called "forming box". The forming box has a profile with an extension that is suitably designed to wrap the film around the forming cylinder and to make the film itself slide on it.

[0004] The tube of film is pulled along by mechanical elements called traction belts, usually operating through friction. Below the forming cylinder there is a horizontal welding unit, called jaw or welding clamp. The welding clamp has an opening and closing movement around the tube of film. When it is open, the welding clamp allows both the tube of film to advance downwards by a distance equal to the length of the envelope that is desired to be obtained, and allows the product that passes through the tube to reach the bottom of the tube itself. Subsequently, the gun closes and welds the tube of film above the product, definitively closing the envelope. Immediately after this phase, a blade cuts the tube of film and lets the finished envelope, filled and closed, fall into the underlying area.

[0005] In the vertical packaging machine the film is unwound and is made to advance with an intermittent motion. When the welding clamp closes, welds and cuts the film, the latter remains still. When the welding clamp is open, the film is, on the other hand, made to advance by a distance equal to the final height of the envelope that is desired to be obtained.

[0006] The thermo-weldable film which forms the envelopes is taken out from a reel usually arranged in the rear part of the packaging machine. When the reel is unwound, the film passes through a series of idle rolls until it reaches the aforementioned forming cylinder. Normally, the operation of unwinding the film from the relative reel is carried out with the traction belts arranged around the tube. In some cases, in order to facilitate the movement of the film, the shaft holding the reel can in turn be motorised.

[0007] In addition to the envelopes manufactured from a film in flexible thermoplastic material, envelopes made up of two distinct layers joined to one another have recently been introduced on the market. Such envelopes indeed comprise a first internal layer in flexible and thermoplastic material (film), having the function of containing the product (snacks, biscuits, lollies, soups, etc.). The internal layer is sealed, once it has been filled with the product, so as to ensure the closure and the sealing for conserving the product itself. The internal layer is thus made in the same manner as a typical pillow bag with a longitudinal welding and two transverse weldings, through a forming tube with forming box and by unwinding the film from a reel in a vertical packaging machine of the type described above.

[0008] Multi-layer envelopes thus comprise an outer part characterised by a rigid wrapping or "sleeve", glued or welded to the internal layer in flexible and thermoplastic material. The external wrapping has some longitudinal pre-cut lines which promote its folding so that, by pressing the outer corners, it can open and give the end envelope a shape like that of a tin can. This allows the envelope to remain rigidly upright once it has been opened and, at the same time, it allows it to take up minimal space on the shelf when it is closed.

[0009] An envelope of the type comprising an internal layer, made of a flexible film realized with a plastic thermo-weldable material, and an external wrapping, made of a rigid sheet material, constrainable to such an internal layer, is described for example in document EP 0 533 648 A1. Document EP 0 533 648 A1 moreover illustrates a method for forming such an envelope.

[0010] The purpose of the present invention is therefore that of making a packaging machine for forming envelopes that is capable of applying a wrapping or "sleeve" made from rigid material, for example cardboard, rigid plastic film, metal foil, etc., on to a classic envelope made from flexible thermoplastic material. The rigid wrapping can be applied to the film through glue or adhesive, and through thermo-welding for thermoplastic materials, as well as through other welding technologies.

[0011] This purpose according to the present invention is achieved by making a packaging machine for forming envelopes as outlined in claim 1.

[0012] Further characteristics of the invention are highlighted in the dependent claims, which are an integrating part of the present description.

[0013] The characteristics and the advantages of a packaging machine for forming envelopes according to the present invention shall become clearer from the following description, given as an example and not for limiting purposes, with reference to the attached schematic drawings, in which:

figure 1 is a perspective view of a production line of envelopes that comprises a packaging machine for forming envelopes according to the invention;

figures 3 to 5 are detailed views of the unit for forming the envelopes belonging to the packaging machine of figure 1;

figure 6 is a perspective view of the transferring carousel of the envelopes belonging to the production line of envelopes of figure 1;

figure 7 is a perspective view of the belt for loading the product into the envelopes belonging to the production line of envelopes of figure 1;

figures 8 to 10 are detailed views of the loading belt of figure 7;

figure 11 is a perspective view of the end welding station belonging to the production line of envelopes
of figure 1; and

figure 12 is a detailed view of the welding station of figure 11.

[0014] With reference to the figures, a production line of envelopes is shown comprising a packaging machine for forming envelopes according to the invention. The packaging machine, of the so called "vertical" type, is wholly indicated with reference numeral 10.

[0015] The production line is provided with a plurality of distinct stations or modules, arranged in sequence with respect to one another, which make it possible to form, fill and seal the envelopes P. The production line firstly comprises a unit 12 for loading sheets S of rigid material, which go to form the external wrapping or "sleeve" of the single envelopes P. The sheets S of rigid material, in a phase prior to being introduced onto the loading unit 12, are conveniently provided with pre-cut lines that promote the subsequent folding, as shall be specified in the rest of the description. Alternatively, the sheets S of rigid material can be provided with pre-cut lines in a suitable work station (not shown) of the production line, operatively connected to the loading unit 12.

[0016] The sheets S of rigid material, once they have been suitably spread, are loaded from the top into the loading unit 12. A device 14 for taking out and conveying the sheets S, takes them out one at a time, loading them onto a horizontal conveyor belt 16. Such a conveyor belt 16, by using suitable perforated belts, holds and transfers, through vacuum technology, the sheets S to the subsequent module, that is to say to the vertical packaging machine 10. The conveyor belt 16 advances with intermittent linear motion.

[0017] Between the loading unit 12 and the vertical packaging machine 10 there can be a gluing device 18, which can operate when each sheet S is applied to the internal portion of the envelope through gluing. The gluing device 18 is capable of applying an adhesive material on the back of the sheet S that forms the wrapping of the envelope P, which is still and in a spread position. The adhesive material then coincides with the internal layer of the envelope P in those points on which it has been decided to make the sheet S and the internal layer of the envelope P itself stick to one another.

[0018] The vertical packaging machine 10 comprises, in a per se known manner, a feeding unit 20 of a flexible film realized with a plastic thermo-weldable material. Such a film will form the internal layer of the envelope P, that is to say the layer for containing the product. The film is taken from a reel 22 arranged at the rear part of the packaging machine 10. When the reel 22 is unwound, the film passes through a series of idle rolls until it reaches a substantially vertical forming cylinder 24, around which the film itself wraps until it assumes a tubular shape. A first vertical welding unit indeed provides for welding, in the vertical direction, the outer edges of the film that are placed over one another, so as to form a tube of film.

[0019] The tube of film is pushed vertically downwards by a pair of lateral motorised belts 26 and 28, arranged outside with respect to the forming cylinder 24 and acting through friction on its circumferential surface, and by a linear pusher 30, arranged inside the forming cylinder 24 itself. Below the forming cylinder 24 there is a second horizontal welding unit 32, or jaw, able to close the lower end of the tube of film through heat-welding.

[0020] The linear pusher 30, actuated by a control that is independent but suitably synchronised with the lateral belts 26 and 28, is inside the forming tube 24 and, therefore, inside the tube of film welded at its lower part. The function of such a linear pusher 30, in addition to that of pushing and accompanying the tube of film, which has been welded at its lower part, downwards, is also that of keeping the tube of film itself tight, as well as that of rigidly supporting it while, in the subsequent phase, the wrapping S is applied around it. The jaw 32, in addition to welding the tube of film on the lower side, also mounts a semicircular-shaped blade 34, intended both for forming the bottom of the tube of film after the horizontal welding, and for cutting the lower portion of the tube of film itself, so as to obtain the internal layer of the envelope P. Such an internal layer of the envelope P is thus welded on the lower side and open on the upper side, so as to form an internal container for the envelope P itself.

[0021] The linear pusher 30 provides for positioning the internal container of the envelope P thus formed in front of an applying and overturning unit 36, arranged on the packaging machine 10 below the jaw 32 and downstream of the gluing device 18, when present. The linear pusher 30 is conveniently provided with a lower flat-shaped tapered end 38, thus allowing the smallest possible amount of space to be taken up inside the internal container of the envelope P and facilitating the operations of introduction and sliding out from such internal container of the envelope P.

[0022] The applying and overturning unit 36 firstly has the function of taking out each sheet S of rigid material, arriving at a spread position from the loading unit 12 and with the glue already applied (when present), and of overturning it according to an angle of approximately 90°, arranging it around the internal container of the envelope P. Basically, the applying and overturning unit 36 is provided with a resting plate 40 for each sheet S, actuated by a control actuator 48 to move from a substantially horizontal position (figure 5), or position for taking out each sheet S from the loading unit 12, to a substantially vertical position (figure 4), or position for applying the sheet S itself around the internal container of the envelope P. The sheet S, being now in the vertical position, is pressed by the plate 40 of the applying and overturning unit 36 against the internal container of the envelope P, also kept tight, allowing the glue to join together the two layers, outer and inner, of the envelope P itself. The envelope P, by effect of the pressure of the plate 40, does not move since the linear pusher 30 is still inserted inside it and keeps it rigidly still.

[0023] Once the sheet S has been applied to the internal container of the envelope P, so as to form the external wrapping, a pair of movable fins or "hands" 42 and 44 (figures 3 and 4), arranged laterally with respect to the plate 40 of the applying and overturning unit 36 and actuated by an independent control actuator 46, rotate of approximately 180° by making the two lateral edges of the wrapping S rest on the backside of the internal container of the envelope P. This operation, facilitated by the presence of the pre-cut lines on the wrapping S, makes it possible to completely wrap such a wrapping S around the internal container of the envelope P (figure 3), so as to make the glue adhere even on the backside. The wrapping S itself is moreover closed, making the two outermost edges stick one above the other, so as to definitively form the envelope P.

[0024] The production line of the envelopes P comprises, downstream of the vertical packaging machine 10, a transferring carousel 50 (figure 6). The transferring carousel 50 in turn comprises a horizontal rotary table 52 on which the newly formed envelopes P are deposited from the linear pusher 30 of the vertical packaging machine 10. Once the linear pusher 30 has been extracted from each envelope P, it is free to be transferred through the rotary table 52 and to be taken out by the rotary table 52 itself through taking out means 54 that can be either of the mechanical type, or of the vacuum technology type.

[0025] The horizontal rotary table 52 of the transferring carousel 50 moves with intermittent rotary motion, so as to position each preformed envelope P at other modules or subsequent stations of the production line. A first station can foresee for example a store 56 for accumulating empty envelopes P. In such a manner it is possible to make lots of empty preformed envelopes P to be accumulated in the store 56 with the purpose of using them at a later moment or for other processes.

[0026] Alternatively or additionally, the transferring carousel 50 can transfer each single empty envelope P to a conveyor belt 58 on which one or more stations 60 are applied (only one of them is partially shown in figure 7) for filling or for loading the product inside each envelope P. The conveyor belt 58 has a substantially horizontal projection and moves with alternate linear motion. It is made up of a main belt 62 on which a plurality of elements 64 for gripping the empty envelopes P are mounted, capable of accompanying such envelopes P, through the subsequent station 60 for loading the product, to the end welding station (described in the rest of the description).

[0027] Each gripping element 64 is equipped with a mechanical clamp (figures 8-10) which opens and closes, grasping at the sides the preformed envelope P at the relative pre-cut lines. This opening and closing movement of the gripping element 64 has the function of both gripping and holding every envelope P, rigidly supporting them, and of opening the envelope P itself, in the subsequent phase, so as to allow the product to be inserted inside it. The gripping element 64 is provided with two symmetrical holding arms 66 and 68, which move together thanks to a cam mechanism with a contrast spring 70. The cam is located in the rear part of each gripping element 64 and, during the phase of transferring along the conveyor belt 58, makes it possible to control the movements of gripping and releasing each envelope P.

[0028] Once each envelope P, empty and open at the top, has been positioned by the conveyor belt 58 at the filling station 60, the conveyor belt 58 itself stops for enough time so as to allow the product loading phase. The product is introduced inside each envelope P from the top, through falling.

[0029] Along the conveyor belt 58, downstream of the filling station 60 it is finally foreseen for there to be a station 72 for the final closure or welding of the envelopes P (figure 11). The envelope P, filled with the product but still open at the top, is transferred from the conveyor belt 58 to the welding station 72. The gripping element 64 releases the relative envelope P and, simultaneously, a mechanical heated jaw 74, belonging to the welding station 72, intervenes so as to weld and close the upper edge of the envelope P itself, that is to say the upper edge of its internal layer made from plastic thermo-weldable material.

[0030] In order to avoid that the upper edge of the film inside of the envelope P forms creases and wrinkles during the closure of the jaw 74 and the subsequent welding, with consequent problems in terms of appearance and in terms of sealing, two small mechanical "fingers" 76 and 78, actuated by an independent control, are introduced in the envelope P itself and keep its upper portion spread, still open, whereas the jaw 74 closes. The jaw 74 is also equipped with a knife with a blade that eliminates the upper edge of the film which, in turn, can be removed by means of a suction device 80. The blade has a straight shape, thus making it possible for the envelope P to have the upper edge closed and flat and have both the upper and lower edge with a conveniently straight shape.

[0031] It has thus been seen that the packaging machine for forming envelopes according to the present invention achieves the purposes previously highlighted.

[0032] The packaging machine for forming envelopes of the present invention thus conceived can, in any case, undergo numerous modifications and variants all covered by the same inventive concept; moreover, all the details can be replaced by technically equivalent elements. In practice the materials used, as well as the shapes and sizes, can be any according to the technical requirements.

[0033] The scope of protection of the invention is thus defined by the attached claims.

Claims

1. Packaging machine (10) for forming envelopes (P) of the type comprising an internal layer, made of a flexible film realized with a plastic thermo-weldable material, and an external wrapping (S), made of a rigid sheet material, constrainable to said internal layer, the packaging machine (10) comprising:

- a feeding unit (20) of the flexible film;

- a loading unit (12) of the rigid sheet material (S) ;

- a forming cylinder (24) substantially vertical, around which the flexible film wraps up to assume a tubular shape;

- a first vertical welding unit, able to close vertically the flexible film tube;

- a second horizontal welding unit (32), able to close in its lower part the flexible film tube and to cut its lower closed portion, so as to form an internal container for the envelope (P) welded on the lower side and open on the upper side,; and

- an applying and overturning unit (36) able to take out each sheet (S) of rigid material, arriving at a spread position from the loading unit (12), and to overturn it according to an angle of approximately 90° to apply it around the internal container of the envelope (P), characterised in that the applying and overturning unit (36) is provided with a resting plate (40) for each sheet (S), actuated by a control actuator (48) to move from a substantially horizontal position, or to take out each sheet (S) from the loading unit (12), to a substantially vertical position, or to apply said sheet (S) around the internal container of the envelope (P).

2. Packaging machine (10) according to claim 1, characterised in that the applying and overturning unit (36) is provided with a pair of movable fins (42, 44), disposed laterally with respect to the resting plate (40) and actuated by an independent control actuator (46), able to rotate of approximately 180° in order to rest the two lateral edges of the sheet (S) on the backside of the internal container of the envelope (P) and to close said sheet (S) around said internal container of the envelope (P), so as to definitely form the envelope (P).

3. Production line for forming, filling and sealing envelopes (P) of the type comprising an internal layer, made up of a flexible film realized with a plastic thermo-weldable material, and an external wrapping (S), made up of a rigid sheet material, constrainable to said internal layer, characterised in that it comprises a packaging machine (10) according to any of claims 1 or 2.

4. Method for forming envelopes (P) of the type comprising an internal layer, made of a flexible film realized with a plastic thermo-weldable material, and an external wrapping (S), made of a rigid sheet material, constrainable to said internal layer, using a packaging machine (10) according to any one of claims 1 or 2, characterised in that it comprises the following steps:

- separately feeding the flexible film and the rigid sheet material (S) to the packaging machine (10);

- forming a flexible film tube along a substantially vertical direction and closing vertically and in its lower part, by welding, said flexible film tube;

- cutting the lower closed portion of the flexible film tube, so as to form an internal container for the envelope (P) welded on the lower side and open on the upper side;

- applying, by bending, a single sheet (S) of rigid material around each internal container of the envelope (P).

5. Method according to claim 4, characterised in that the step of applying each sheet (S) of rigid material around each internal container of the envelope (P) further comprises the step of overturning the single sheet (S) of rigid material according to an angle of approximately 90° to apply it around the internal container of the envelope (P).

6. Method according to claim 4 or 5, characterised in that the application step of each sheet (S) of rigid material around each internal container of the envelope (P) is made by gluing.

7. Method according to claim 4 or 5, characterised in that the application step of each sheet (S) of rigid material around each internal container of the envelope (P) is made by thermo-welding.

8. Method according to any one of claims 4 to 7, characterised in that the step of applying each sheet (S) of rigid material around each internal container of the envelope (P) further comprises the step of bending, according to an angle of approximately 180°, the two lateral edges of the sheet (S), to make them rest on the backside of the container inside the envelope (P) and to close said sheet (S) around said internal container of the envelope (P), so as to definitively form the envelope (P).

Drawing