A MACHINE FOR CONTINUOUS MANUFACTURING OF NETTING BAGS

Abstract: A procedure for the continuous manufacturing of netting bags,an improved machine for the implementation of said procedure and the netting bags coming out therefrom of the type which is using a nett­ ing tube being cut at the ends to shape up closed containers after being filled. The process is generating the lateral feeding of bands of thermoweldable material for a concurrently application to the bags at their external and/or internal portions,in certain cases being determined thereby some areas of the thermoweldable materials without interruption from the bag head to the bag bottom; restrict­ ed areas to the bag head and bottom and head derived flaps. The band flowing circuit is external and/or internal from the netting body. Bands are cut by two horizontally actuated opposing movable knives, downwardly placed at the band guiding and driving area and at the entry into the machine of the bands.

Description: The present invention refers to a machine for preparing net bags filled with products, such as fruits or vegetables, and closed at the top and bottom ends by thermowelding, from a sleeve of thermoweldable netting material, as set forth in the preamble of claim 1. A machine of this type is known from EP-A-0302460. This document discloses a machine for preparing net bags filled with products, such as fruits or vegetables, comprising a vertical tube open at its lower end for the introduction of the product into the bag and surrounded by a sleeve of netting material which is withdrawn from the tube by a pair of rollers for the controlled downward feed of the netting material. The machine comprises another two pairs of rollers for drawing down plastic laminar bands and two mutually opposed sliding heads, each carrying a cutter blade to act in conjunction with another fixed blade. During operation of the machine, laminar bands are fed downwardly in front of the sliding heads until the leading edges of the plastic bands are at the same level as the lower edges of the sliding heads. Then, the sliding heads are moved towards each other so that they engage the plastic bands which are adhered to the sliding heads by suction means associated to the sliding heads. Upon further movement of the sliding heads towards each other, the plastic bands are cut by the cutter blades and are subsequently brought into contact with the netting material which is clamped between the sliding heads and then thermowelded along three horizontally extending thermowelding lines by respective thermowelding means disposed in the sliding heads. Upon termination of the thermowelding, the netting material sandwiched between the pieces of cut plastic bands thermowelded thereto is cut between the two uppermost welding lines to separate the net bag filled with products from the trailing netting material which is, by the process previously explained, closed at its bottom end by thermowelding to receive the next charge of products. Due to this structure of the machine, the net bags are provided with pieces of thermoweldable band material at their top and bottom ends only. From ES-A-8700529, a machine for preparing net bags filled with products is known by which bands of thermoweldable material can be applied to the net bag in such a manner that the bands extend continuously from the bottom to the top end of the net bag. It is neither possible to apply pieces of band material to the top and bottom ends only nor to provide the net bag with a flap suitable for bearing labels and the like. It is the object of the invention to provide a machine as set forth above by which, in accordance with the actual desire of the user, thermoweldable band material may be applied to the top and bottom ends of the net bag only, or band material which extends from the bottom to the top, either inside the net bag or outside thereof, or both, or continuously extending band material and band material pieces at the bottom and the top ends in combination, or even band material forming flaps for the application of labels and the like. This object is attained by the features of claim 1. Preferred embodiments of the invention are subject matter of the dependent claims. It is the essential idea of the invention that the machine comprises two feeding paths for feeding thermoweldable band material to the netting material to be thermowelded to close the net bags at their top and bottom ends. Said feeding paths being independent of each other and being selectable at the choice of the user dependent on the kind of equipment of the net bag to be produced by means of the machine. One of the feeding paths is adapted to provide the net bags with pieces of band material at the bottom and top ends only whereas the other feeding path is adapted to provide the net bag with thermoweldable band material extending continuously from the bottom to the top end either inside or outside the net bag, or both. Thus, the second feeding path has a different configuration dependent on whether the band is to be applied inside or outside the net bag. The invention is now explained in detail with reference to the accompanying drawings showing a preferred embodiment of the machine. In the drawings: Fig.1 shows a frontal view of the machine illustrating the feed path of two bands of thermoweldable material to be applied to the net material outside the net bag formed therefrom and continuously running from the bottom to the top of the net bag; Fig.2 is a similar view showing two feed paths for applying thermoweldable bands to the net bag, one running continuously from the bottom to the top and the other being discontinuously applied to the bottom end and the top end only; Fig.3 is a view similar to Figs. 1 and 2 showing feed paths adapted for the application of two thermoweldable bands which extend continuously between the bottom and top ends of the net bag, one inside and the other outside thereof, and of a third thermoweldable band extending discontinuously in pieces, one being applied to the bottom end and the other to the top end of the net bag; Fig.4 is a view showing the application of two pairs of thermoweldable bands to the net bag, one pair extending on both sides of the net bag outside thereof from the bottom to the top ends and the other pair forming pieces at the bottom and the top ends, wherein one of the top end pieces forms a flap; Fig.5 is a view showing two pairs of thermoweldable band material applied to the net bag, one pair extending inside the net bag between the bottom and top ends thereof whereas the other pair forms pieces at the bottom end and the top end, one of them being extended to form a flap; Figs.6 and 7 illustrate the application of a single thermoweldable band extending between the bottom and top ends of the net bag and a pair of bands applied to the net bag as pieces at the bottom and top ends, wherein one of them forms a flap, wherein Fig. 6 shows the application of the continuous band outside the net bag and Fig. 7 shows the application of the continuous band inside the net bag; Fig.8 shows the application of pieces of thermoweldable band material at the bottom and top ends of the net bag only, whereas one of the top end pieces is extended to form a flap; Figs.9 and 10 are side views; and Figs.11 and 12 are top views of characteristic features of the machine showing details of the band feeding mechanisms. In Figs. 1 to 8, the types of net bags prepared by the machine are shown as side views along with machine members. In accordance with Fig. 1, bands of thermoweldable laminar material are supplied from rolls 1 and 2 and are guided via a convenient number of rolls 3 and 4 and are fed to opposite sides of a constricted portion 5 of the net bag 6 formed from tubular netting material 7 withdrawn from a cylindrical carrier tube 8. Cutting and welding of the thermoweldable bands applied externally to the constricted portion 5 of the net bag is conventionally obtained by a movable arrangement comprising a carrying body 9 provided with thermowelding edges 10, a knife 11, and punches 12 designed for piercing the bands and the net sandwiched therebetween to form cuts of finger holes 50 and 51. Figs. 2 to 8 show another feed path for thermoweldable band material 15 by which at least one thermoweldable band material 15 is delivered directly to the cutting and welding area of the machine. The respective arrangement, as shown in side views of Figs. 1 to 10 and top views of Figs. 11 and 12, comprises a rectangular-shaped metal laminar sheet 13 horizontally arranged and having an entrance edge 14 upwardly curved to receive the thermoweldable band material 15 and the opposite edge 16 being curved in the opposite sense for the delivery of the band material to the cutting and welding area of the machine. Underneath the sheet 13 is another metal laminar sheet 17 which, together with sheet 13, defines narrow space within which the thermoweldable band 15 is running. The top metal sheet 13 is provided with a plurality of rectangular, parallel and equidistant openings through which annular projections 18 associated to a transverse roller provided on a horizontal shaft protrude into the space defined by the metal sheets 13 and 15, the projections engaging the top face of the band 15, the lower band face being supported by a roller 19, the surface of which is covered with a soft material or the like at at least some annular areas associated to the annular projections of roller 18. Thereby, a smooth traction of the band 15 is obtained without any possibility of sliding towards the central area of the machine, where the bands of thermoweldable material will be welded to the net material and cut. Movable knives 20 oppositely mounted are moved towards each other in synchronism with the other elements of the machine for cutting the band(s) 15 of the thermoweldable material. It is a characteristic of the machine that no suction cups or other pneumatic members exist in the cutting and welding area since holding of the thermoweldable bands during the implementation of the operations explained above by means of such suction cups or the like is not at all necessary. Another characteristic of the new machine is the existence of rods 21 and 22 horizontally arranged and pivotally mounted to a support 23, said rods 21 and 22 being guided by an intermediate support 24 which automatically determines their opening or closing in accordance with the actual position of the movable body 9a of the machine when the closing of the net bag and the cutting and welding operations of the bag, along with the bands supplied thereto, is performed. In this way, a smooth tubular constriction and a properly flattened shape of the net material prior to the welding and cutting process is obtained. The machine can be completed using arrangements performing ancillary operations, such as applying two or more parallel bands inside or outside the bags for carrying advertising information or for providing an aesthetic design thereto. The band length of the thermoweldable band material is dependent on whether a handle only at one or the other side of the formed bags is to be prepared or the bag is to be provided with a flap for having labels affixed thereto or information printed thereon. The band length is adjusted by means of pneumatic cylinders 25 at each side of the machine, horizontally supported and having the cylinder shaft perpendicular to the travel of netting material upon forming the net bags, said cylinder 25 being supported by a support 26 fitted to a movable arm 27 sliding on fixed guides affixed to the machine frame. The pneumatic cylinder 25 houses a piston having a stem 28 provided with a rack length 29 and a threaded length 30 at its end which allows the adjustment of the piston's forward travel relative to an abutment member 31 by means of one or two adjustement nuts. In this way, the amount of rotation of a guiding roller 32 associated and meshing with the rack is determined and thereby, the amount of rotation of a wheel 33 and of a roller train 18 and 19 associated thereto causing the band feed is determined. From aforementioned Figs. 1 to 8, the travel of the bands of thermoweldable material fed to the netting material is well understood. The result obtained by the various kinds of band feed is understood from the side views and profiled views of net bags shown in figs. 1 to 8. As may be learned from Figs. 3 to 7, the net bags may be provided with thermoweldable bands inside as well as outside the netting material forming the net bag. According to these figures, at least one thermoweldable band may be provided by a roll 34 or two bands may be provided by rolls 34 and 35 and duly guided by roller sets and fed to the central area of the machine where the band is provided to the netting material outside thereof (Figs. 3 and 6) or inside thereof by feeding it between the netting material 7 and the tubular carrying body 8, as shown in Figs. 3, 5 and 7, in accordance with the user's desire. These bands are adapted to extend continuously from the bottom to the top ends of the net bag, and they are concurrently cut and welded with the other band or bands of thermoweldable material making up reinforcing and labelling areas of the bag's bottom and top portions. From Figs. 1 to 8, the manner in which the bands of thermoweldable material supplied by rolls 1 and 2 are guided to run on different feed paths in accordance with the lengths desired to be set up at the outside of the net bag can be learned. When the bands are to extend outside the net bag continuously from the bottom to the top portions on one or both sides of the bag according to Figs. 1, 2 and 3, respectively, the bands of thermoweldable material are not guided through the feed paths between the metal sheets 13 and 17 but, rather, through slots 36 and 37 transversely extending in plates 38 and 39, as seen in Figs. 1 to 4, 6, 11 and 12. The latter plate 39 is provided with extensions 40 determining a central rectilinear area 41 adapted to the lower portion of the netting material 7, promoting in this way the constriction of the netting material before clamping same between clamping bodies 9 and 9a prior to the welding process. The bags according to Fig. 1 are provided with two rectangularly-shaped side bands 42 fully extending over the bag and its contents, whereas the bag according to Fig. 2 has one band continuously extending from the bottom to the top ends outside the net bag, and the bag of Fig. 3 has one band continuously extending outside the bag from the bottom to the top ends, whereas another band extends inside the net bag from the bottom to the top ends, the latter being supplied by roll 34. The bag according to Fig. 4 is externally provided with two bands 44 and 45 supplied by rolls 34 and 35, and is additionally provided with band pieces forming reinforcing areas 46 and 47 at the top and bottom ends of the bag, one of them forming a flap for the attachment of labels and the like. The bags prepared by the machine of the invention are provided with two or more continuous or discontinuous welding lines 48 and 49 defined by the welding bands 10 of the active clamping body 9 which is additionally provided with punches 12 for punching cuts for finger holes 50 and 51. The top edge 52 and the bottom edge 53 of the pieces of thermoweldable band material welded to the top and bottom ends of the net bag are formed by cutting knife 11 associated to the clamping body 9, whereas the bottom edge 55 of the pieces of thermoweldable material 15 welded to the top end of the net bag are formed by cutting knives 20. At the bottom end of the bags, the welding line 54 puts together the thermoweldable band material with the net material 7 forming the bag. It may be seen from the figures that knife 11 is located between the welding projections 10 producing the weld lines 48 and 54. The length of the flap 56 according to Fig. 5 can be adjusted by governing the stroke of the rack 29 associated to the respective pneumatic cylinder 25, and the flap can be used for affixing a label 57 thereto containing optional inscriptions and graphics or a bar code. In the case of fixing labels, for instance, at the flap 56, an ancillary arrangement can be used, which is not illustrated in the drawings, which might improve easy placing of labels without any wrinkles and based on the operation of small pneumatic cylinders.

Claims: A machine for preparing net bags (6) filled with products, such as fruit or vegetables, and closed at their top and bottom ends by thermowelding from a sleeve of thermoweldable netting material (7), comprising: a carrier tube (8) carrying on its circumference a sleeve of said thermoweldable netting material (7) in accumulated fashion and serving as a feed means for the product to be filled into the formed net bags (6); means (13;36,37;40) for feeding thermoweldable band material (15,42,44,45) to at least a portion (5) of said netting material (7) withdrawn from the carrier tube (8), to be attached to the netting material (7) by thermowelding; clamping means (9,9a) for clamping the portion (5) of said netting material (7) withdrawn from said carrier tube (8) with said thermoweldable band material (15,42,44,45) being fed to said clamped netting material portion (5), thermowelding means (10) associated with said clamping means (9,9a) for thermowelding said netting material portion (5) and said band material (15,42,44,45) supplied thereto along at least two welding lines (48,49,54) for closing the net bag (6) formed from said netting material (7); said means for feeding comprising a pair of first feed paths (13) for feeding thermoweldable band material (15) to said clamping means (9,9a); first cutting knives (20) for cutting said band material (15) and being disposed in said first feed paths (13); and a second cutting knife (11) for separating a formed net bag (6) filled with products from the trailing netting material (7) between two (48,54) of said welding lines (48,49,54), characterized by said first knives (20) being operated only concurrently with the thermowelding means (10) when applied to said clamped netting material portion (5) to provide the net bags (6) with said band material (15) at their top and bottom ends only, and second feed paths (36,37;40) for feeding thermoweldable band material (42,44,45) to said netting material (7), said second feed paths being out of the operational range of said first knives (20) to provide the net bags (6) with band material (42,44,45) extending from the top to the bottom ends thereof. A machine as set forth in claim 1 wherein the first feed paths each comprise a pair of metal sheets (13,17) extending horizontally upstream of the first knives (20) and leaving a vertical space therebetween for guiding the band material (15) therethrough, and a pair of rollers (18,19) partially extending through openings in said metal sheets (13) and having a plurality of annular projections of a material of low hardness engaging said band material (15). A machine as set forth in claim 2 wherein one of said rollers (18,19) is driven by a toothed wheel in turn driven by a pinion (32) which meshes in a rack (29) affixed to the stem (28) of a pneumatically driven piston. A machine as set forth in claim 3 wherein the stem (28) is provided at its end with a threaded length (30) having at least one adjustment nut which, in cooperation with an abutments means (31), determines the stroke of the piston. A machine as set forth in any one of the preceding claims comprising horizontally extending rods (21,22) pivotally mounted in a support (23) and guided by an intermediate support (24) and performing a closing and opening movement, respectively, in conjunction with the movement of the clamping means (9,9a) into the clamping and releasing positions, respectively, to reduce the width of the portion (5) of the netting material to be clamped by the clamping means (9,9a).

Inventors: MARSAL, EZEQUIEL GIRO
Applicants: EMPAC S.A.
Application year: 1990
Main classification: B65B9
IPC codes: B65B61, B31B41, B65B9, B65B25, B65D30