PACKAGING MACHINE EQUIPPED WITH AN IMPROVED WELDING AND CUTTING DEVICE

Abstract: A packing machine, in which the packaging is carried out of products (13) fed by free-falling inside a cradle-shaped length of a packaging material (15), which is provided with a welding/cutting device for welding and cutting opposite edges of packaging material, is capable of accomplishing a continuous weld on three sides of the product-containing packaging material, and of removing ear-shaped scrap portions of said packaging material, generated by the weld.

Description: The present invention relates to a packaging machine equipped with sealing and cutting device. FR-A-2 129 766 relates to packaging machines, in which the product to be packaged is fed by gravity into a cradle-shaped length of a packaging material, unwound from two opposite bobbins. The cradle-shaped length of packaging material partially wraps the product and, once that a suitable unwinding of packaging material is accomplished, a sealing and cutting device finishes the package, with simultaneously restoring the continuity of the material unwound from both bobbins, which is therefore ready to receive the subsequent product which is being fed. A so-constructed packaging machine causes a pack or package to be formed which, owing to the type of welding device, shows two welds oriented in the transverse direction relatively to the fed packaging material, in the nearby of the peripheral area which constrains the product, and two welds oriented in the longitudinal direction relatively to the packaging material fed, accomplished side-by-side to the packaged product, and such as to produce a pair of longitudinal extended marginal end portions of packaging materials not engaged by the product, and positioned side-by-side relatively to said product. More precisely, during each operating cycle of the device, essentially one single transversal welding is carried out, which, on the other hand, by acting as a so-called "weld-cutter" determines the sealing of the finished pack, and simultaneously restores the continuity of the packaging material which is unwound from both bobbins. These extended longitudinal end portions of packaging material form two side "ears" in the finished pack which give the pack an aesthetically objectionable appearance. Furthermore they cause handling problems as well as operating problems in case the pack has to undergo successive processing steps. If, on the contrary, said side "ears" have to be removed, first of all quasi-intersecting transversal welds and longitudinal welds have to be provided, in order to facilitate the separation of said "ears" of packaging material from the finished pack, with a removal of the same "ears" once that said pack is finished and evacuated from the packaging machine. In this case too, the above-said "ears", or material appendices generated by the packaging welding generate handling problems during the treatment steps when the finished pack leaves or after it has left the packaging machine. GB-A-1 052 312 shows a cutting and seaming apparatus in which the separated lateral edges created by the cutting and seaming operation are removed by a simple vacuum conduit. The purpose of the present invention is of solving the above cited problems by means of a packaging machine which is capable of accomplishing product packs, in which the product to be packaged is fed to a cradle-shaped length of packaging material, and said length of packaging material is welded along its periphery, and which, simultaneously to the formation of the pack, is capable of removing side "ears" from said pack. This purpose according to the present invention is achieved by providing a packaging machine equipped with a sealing and cutting device according to claim 1. The constructional and functional characteristics and the advantages of a packaging machine equipped with sealing and cutting device according to the present invention will result more clearly from the following disclosure, referring to the relevant drawings, in which: Figure 1 shows a side elevation view of a machine according to the present invention, Figure 2 shows a transversal sectional view of a detail of the sealing and cutting device in its open position, Figure 3 shows a magnified partially sectional view of the sealing and cutting device as shown in Figure 1, Figure 4 shows a partially sectional plan view, Figure 5 shows a sectional view of the sucking device of the machine according to the invention, made along the path line V-V of Figure 6, and Figure 6 shows a sectional view according to path line VI-VI of the sucking element of Figure 5. Referring to Figure 1, a portion of a packaging machine is schematically shown in which, mounted on a frame 11, a welding and cutting device for a packaging material 12 containing a product schematically shown in 13, is provided. The packaging material 12, such as, a plastic film, is unwoud from two bobbins 14, supported on the frame 11 at opposite sides of the welding and cutting device and, in correspondence of said welding and cutting device, defines a cradle-shaped length, indicated by the reference numeral 15, inside which the product 13 drops, which is stepwise fed and unloaded by gravity by a feeder means 16, such as a conveyor belt. On the frame 11 a welding and cutting device is furthermore installed, said welding and cutting device essentially comprising blade elements 17 and counter-blade elements 18, respectively, acting as a stationary blade and as a mobile counter-blade, which can be driven to carry out to-and-fro movements, so as to accomplish the pack. Both said blade element 17 and counter-blade element 18 comprise an upper horizontal portion 19, which extends throughout the transversal width of the packaging material 12, and at least two longitudinal, vertical, side portions 20, perpendicularly extending downwardly from the upper horizontal portion 19. According to the particular, advantageous arrangement according to the present invention, in the areas of intersection between the upper horizontal portion 19 and the longitudinal side portions 20 an omega-shaped element 21 is provided, which is operatively connected with said upper horizontal transversal portion 19. In the herein depicted example, the blade element and the counter-blade element are constituted by wire resistors, and any fortuitous contacts between the transversal blade portion and the longitudinal blade portions, which would cause the welding/cutting unit to become unserviceable, has to be prevented. On the other hand, said portions of the blade or/and counter-blade elements have to be installed as close to each other as possible, in order to facilitate the subsequent operations of separation of side end portions 22 of said cradle-shaped length 15, which are generated by the welding/cutting action performed by said blade elements 17 and counter-blade elements 18. Preferably, in correspondence of said cradle-shaped length 15 and of said welding/cutting device, sensor means 23 for the selective actuation of unwinding means 24 which control the unwinding of the bobbins 14, and of a motor means 25 for reciprocating said movable counter-blade elements 18 - with said motor means 25 reciprocating as shown by the arrow 26 - are provided. Flanked to said longitudinal side portions 20 on said stationary blade element 17, or on the frame 11, two sucking elements 27 are installed, said sucking elements 27 having the shape of cylindrical box-like elements, provided with a large port 28 on their side surface, positioned next to said side end portions 22. Both sucking elements 27 are connected through ducts 29 to a central exhausting manifold 30 which is connected to a vacuum source (nor shown in the figures). Inlet ports 31 of said central manifold 30 are selectively closed by a pivotally swinging shutter wall 32 driven by an actuator cylinder 33, also operatively connected to said sensor means 23. A packaging machine according to the present invention operates as follows. The products 13 to be packaged are fed in equally spaced intervals by the conveyor belt 16 so as to be deposited by gravity into the interior of the cradle-shaped length 15 of the packaging material defined between the welding and cutting device 17, 18 in its open condition (Figure 2). The sensor means 23 detect the passage of the product 13, and consequently command the stoppping of the conveyor belt 16, as well as the stopping of the bobbin unwinding means 24, while simultaneously activating the reciprocating motor means driving the movable counter-blade element 18. As soon as the stationary blade element 17 and the movable counter-blade element 18 come into contact and the welding/cutting action is performed, the sucking elements 27 are activated by opening the ports 31 of the central manifold 30. The side end portions 22 of said cradle-shaped length 15 i.e., the "ears" generated by the welding/cutting action, are thus ultimately separated from the packed product 13, and are intaken into the interior of the sucking elements 27. This is of course facilitated according to the present invention by the particular positioning of the omega-shaped elements 21 on the areas of intersection between the upper horizontal portion 19 and the side longitudinal portions 20 of the blade and counter-blade elements 17, 18. The above-said suction action is carried out during an extremely short time, such that the side end, scrap portions 22 are removed, after which the actuator cylinder 33 moves the shutter wall 32 back into its shut position, and packaging cycle can continue. Advantageously, the suction can favour the cooling of the welds, as well as the stability of the so-accomplished pack. In this way, according to the present invention, the problem is solved of obtaining a perfectly finished pack, free from unnecessary packaging material, with the presence of said superfluous scrap packaging material, which could in some way prevent the packaged product from being correctly handled inside the packaging machine being simultaneously eliminated.

Claims: Packaging machine equipped with a welding and cutting device, of the type comprising at least in combination a product-feeding means (16), to stepwise feed, and to unload a a product (13) to be packaged by gravity into a transversely sealed length of a packaging material (12) which is unwound from two bobbins (14), supported at opposite sides of a sealing and cutting :device (17,18) providing the end seals of the package, sensor means (23) suitable for selectively controlling the unwinding of said packaging material from said two bobbins (14), said sensor means being operatively connected to a motor means (25) for reciprocating the sealing and cutting device (17, 18), which comprises blade element (17) and counter-blade elements (18) movable respectively to wards each other, such as to provide the transverse end, and the longitudinal seals at the longitudinal and tranverse overlapping edges of said packaging material (12), wrapping said product, characterised in that sucking elements (27) are provided side-by-side to said blade and counter-blade elements to suck the cut marginal end portions produced at said longitudinal seals (22) of said package (12) defined by the welding/cutting action of said blade and counter-blade elements (17, 18) said sucking elements (27) being constitued by box-like elements provided with a large port (28), said box-like elements being installed on a stationary frame (11) of the machine, and being connected to ducts (29) leading a to central exhausting manifold (30), means being provided for the activation of said sucking elements (27), comprising a shutter wall (32) shutting ports of said central manifold (30) leading to said ducts (29), said shutter (32) being pivotally actuated actuated by an actuator (33), connected to said sensor means (23) to open and close said ports. Packaging machine according to claim 1, characterised in that said blade elements (17) and counterblade elements (18) are provided with an upper horizontal portion (19) transversal to said packaging material (12), and at least two longitudinal side portions (20) perpendicularly extending downwardly from said upper transversal portion (19), there being provided on the areas of intersection of said upper transversal portion (19) and said longitudinal side portions (20) omega-shaped elements (21) which are operatively connected with said upper transversal portion.

Inventors: BALLESTRAZZI, ARIS, TASSI, LAMBERTO
Applicants: SITMA S.P.A.
Application year: 1989
Main classification: B65B51
IPC codes: B65B51, B26D7, B29C65