Method and device for feeding wrapping material to a wrapping machine

Abstract: A method and device (9) for successively feeding portions (8) of wrapping material to a wrapping machine (1), whereby the portions (8) are drawn towards a transfer station (5) by gripping devices (47) on the forward branch (36) of a conveyor (38) having two belts (45) and the return branch (37) of which is located facing a folding seat (7) on the wrapping machine (1); at the transfer station (5), each portion (8) on the forward branch (36) of the conveyor (38) being moved through both belts (45) and towards a respective folding seat (7) by a respective product (4) fed perpendicularly to the transportation surface (49) of the conveyor (38).

Description: The present invention relates to a method of feeding a wrapping machine with portions of wrapping material. On wrapping machines for forming overwrappings of paper or transparent material about a succession of products, the products are fed successively to a transfer station where each product is inserted inside a folding seat together with a portion of wrapping material, which, as the product is inserted inside the seat, is folded into a U about the product and subsequently closed by folding devices cooperating with the seat to form a tubular wrapping about the product. On known wrapping machines of the aforementioned type, the portions of wrapping material are normally formed from a continuous strip fed towards the transfer station by two opposed push rollers downstream from which are provided, in succession: a gumming device, in the case of paper material, for gumming given points on the opposite surface of the strip to that facing the folding seat; a cutting unit comprising a fixed blade and a movable blade, for cutting the strip into portions; and a guide device extending through the transfer station and comprising guide strips positioned contacting the opposite surface of the portions to that facing the folding seat and defining a transportation surface perpendicular to the direction in which the products are fed towards the folding seat. Consequently, the wrapping material is pushed towards the transfer station and, what is more, is gummed on the side facing the guide strips. A first drawback of the above method is the possibility of the leading edge of the continuous strip remaining attached to the fixed blade on the cutting unit, thus resulting in curling of the strip when it is pushed forward by the push rollers. If the above drawback is overcome as in EP-A-31515 (which corresponds to the preamble of claims 1 and 8), withdrawal of the portions, for any reason, from the transfer station inevitably results, in any case, in fouling of the guide strips by the gum with which the portions are coated. It is an object of the present invention to provide a method of feeding portions of wrapping material to a wrapping machine, designed to overcome the aforementioned drawbacks. According to the present invention, there is provided a method of feeding portions of wrapping material to a wrapping machine, whereby the portions having a first and second surfaces opposite to each other are fed successively, by feeding and guide means defining a transportation surface for said portions, to a transfer station wherein each portion is positioned with its second surface facing a folding seat so as to interfere with a respective product which is moved through said feeding and guide means and towards said folding seat in a direction substantially perpendicular to said transportation surface; the portions being drawn by the feeding and guide means towards the transfer station; the feeding and guide means comprising means for gripping said portions, and transportation means integral with said gripping means; characterized by the fact that said transportation means are activated for bringing said gripping means successively into engagement with said second surface of the portions, and so drawing the portions, via said gripping means, along the transportation surface and through the transfer station. The portions are thus drawn, as opposed to pushed, towards the transfer station, thus eliminating any danger of the strip curling, and may be gummed on the opposite surface to that contacting the transportation means, thus eliminating any possibility of the transportation means being fouled by the gum. According to a preferred embodiment of the above method, said transportation means comprise two looped belts separated by a distance greater than the width of the portions, and comprising respective forward branches traveling towards the transfer station and facing said second surface of the portions, and respective return branches facing said seat; the gripping means located along said forward branches defining said transportation surface; and each portion being moved by the respective product through both the forward and return branches of said belts as it is inserted inside said seat. Preferably, the leading end of each portion is engaged by said gripping means; and the portions are drawn upwards towards the transfer station by the feeding and guide means. Preferably, the portions are formed from a continuous strip, the leading end of which is engaged by the feeding and guide means and drawn towards the transfer station; and each portion corresponds with a leading portion of the strip, which is cut off the strip when positioned astride the transfer station. The present invention also relates to a device for feeding portions of wrapping material to a wrapping machine according to claim 8. According to the present invention, there is further provided a device for feeding portions of wrapping material to a wrapping machine, the portions having first and second surfaces opposite to each other, and the device comprising feeding and guide means defining a transportation surface for feeding the portions to a transfer station where each portion is positioned, in use, with its second surface facing a folding seat so as to interfere with a respective product movable through said feeding and guide means and towards said folding seat in a direction substantially perpendicular to said transportation surface; the feeding and guide means comprising means for gripping said portions, and transportation means integral with said gripping means; characterized by the fact that said transportation means are arranged so as to bring said gripping means successively into engagement with said second surface of the portions, and so draw the portions, via said gripping means, along the transportation surface and through the transfer station. The invention will be described by way of example with reference to the accompanying drawings, in which: Fig.1 shows a partially sectioned, schematic side view, with parts removed for simplicity, of an overwrapping machine featuring a device for feeding portions of wrapping material in accordance with the teachings of the present invention; Fig.2 shows a plan view of a detail in Fig.1. Number 1 in Fig.1 indicates a known type of overwrapping machine comprising a supply wheel 2 having a number of peripheral transportation pockets 3 and rotating about its axis for successively feeding products 4 to a transfer station 5. Station 5 is located between wheel 2 and a wrapping wheel 6 having a number of peripheral seats 7 and rotating about its axis, parallel to the axis of wheel 2, in the opposite direction to and at the same surface speed as wheel 2. At station 5, each seat 7 is designed to receive, in known manner, a respective product 4 and a portion 8 of wrapping material fed to station 5 by a feed device indicated as a whole by 9. Device 9 provides for successively arresting portions 8 between pocket 3 and respective seat 7 in station 5, so as to enable product 4, when pushed radially outwards of pocket 3 and towards wheel 6 by a known push device (not shown), to insert portion 8 inside seat 7 and fold it in a U about product 4. Portion 8 is subsequently folded fully about product 4 in known manner by activating two folding devices 10 and 11 located on either side of the mouth of seat 7 in station 5, and which provide in known manner for forming a tubular wrapping (not shown), one side of which consists of two opposite portions (not shown) of portion 8 folded integrally one on top of the other. Should portion 8 consist of paper material, said two portions (not shown) are connected by means of gum deposited by gumming devices 12 on surface 13 of portion 8 facing wheel 2 when portion 8 reaches station 5. Feed device 9 comprises a reel (not shown) for a continuous strip 14 of wrapping material, which is run off through a known type of compensating store 15 to a first conveyor 16 of device 9. Conveyor 16 comprises three permeable belts 17 (Fig.2), each having a number of through holes 18, and each looped about two pulleys 19 and 20 defining, on conveyor 16, a forward branch 21 and a return branch 22, each narrower than strip 14. Pulley 19 is a known type of suction pulley comprising a powered outer rim 23 having a number of radial through holes 24 at and/or between belts 17, and mounted on a fixed inner drum 25 so as to rotate anticlockwise (in Fig. 1) about drum 25 and move forward branch 21 of conveyor 16 in direction 26 extending parallel to the Fig.2 plane, perpendicular to the respective axes of wheels 2 and 6, and vertically upwards towards station 5. Drum 25 presents an outer chamber 27 extending over the arc of contact between rim 23 and belts 17 and communicating with a suction conduit 28 formed centrally through drum 25. Between pulleys 19 and 20, the inner surface of forward branch 21 travels contacting a perforated wall 29 of a suction box 30 extending through a first cutting-unit indicated as a whole by 31 and which, in certain cases, may be eliminated as explained in more detail later on. Cutting device 31 comprises two fixed blades 32 aligned on either side of box 30 between branches 21 and 22; and two movable blades 33 projecting radially outwards from the periphery of a powered roller 34 rotating clockwise (in Fig.1) about an axis perpendicular to the Fig.1 plane and parallel to the respective axes of wheels 2 and 6. Pulleys 20 are fitted on to the same shaft 35 located between the forward branch 36, facing wheel 2, and the return branch 37, facing wheel 6, of a second conveyor 38 extending vertically through station 5 and between wheels 2 and 6. Conveyor 38 comprises two shafts 39 and 40 parallel to each other and to shaft 35, and located at the opposite ends of a supporting frame 41 extending through station 5. More specifically, shaft 39 extends in the gap between branches 21 and 22 of conveyor 16; and one of shafts 39, 40 is powered for moving forward branch 36 of conveyor 38 in vertical direction 42 parallel to direction 26. The opposite ends of shafts 39 and 40 are fitted with respective pairs of pulleys 43 and 44 supporting two looped belts 45 parallel to each other and to belts 17 and separated by a distance greater than the width of strip 14. Frame 41 comprises two suction boxes 46 located inside the forward and return branches of each belt 45 and communicating with suction conduits (not shown) formed through appendixes 47 integral with and extending from each belt 45 towards the other belt 45. Each appendix 47 corresponds with an appendix 47 on the other belt 45, so that the distance between each pair of corresponding appendixes 47 is less than the width of strip 14. Moreover, each appendix 47 presents, on the outward-facing surface, a number of suction holes 48 communicating with said suction conduits (not shown). Said outer surfaces of appendixes 47 define, along forward branch 36 of conveyor 38, a transportation surface 49 of conveyor 38. The central portion of shaft 40 is fitted with a roller 40a positioned facing a pair of gumming devices 12. Forward branch 36 of conveyor 38 extends through a further cutting device 50 located upstream from station 5 and at a distance from gumming devices 12 substantially equal to the length of portion 8. Cutting device 50 comprises a fixed blade 51 mounted outwards of conveyor 38, facing branch 36, and parallel to shafts 39 and 40, and which presents a cutting edge facing and slightly outwards of transportation surface 49. In addition to fixed blade 51, which is longer than the width of strip 14, device 50 comprises a corresponding movable blade 52 projecting radially outwards from the periphery of a powered roller 53 supported on boxes 46 between branches 36 and 37 and rotating anticlockwise in Fig.1 about an axis perpendicular to the Fig.1 plane and parallel to the respective axes of wheels 2 and 6. As shown in Fig.1, fixed blade 51 is located immediately downstream, in direction 42, from a cutting station 54 extending between shaft 35 and fixed blade 51 along forward branch 36 of conveyor 38. At cutting station 54, cutting device 50 comprises a detaching member 55 having a suction device 56 and located outwards of conveyor 38, on the same side as fixed blade 51, so as to oscillate between a gripping position, wherein member 55 is substantially coplanar with the cutting edge of fixed blade 51, and an operating position wherein member 55 is substantially coplanar with transportation surface 49. Finally, at station 5, feed device 9 comprises a known type of folding spindle 57 defining a passage 58 of the same section as pockets 3 and seats 7. In actual use, after running through store 15, strip 14 contacts conveyor 16 on the outer surface of pulley 19, which, by virtue of the suction through holes 24 in rim 23, feeds the leading end of strip 14 to forward branch 21 of conveyor 16. Along forward branch 21, strip 14 is held contacting belts 17 by the suction through wall 29 of box 30, and, if necessary, is engaged by cutting device 31, which makes two partial lateral cuts (not shown) in strip 14 for defining, on strip 14, the end folds (not shown) of portions 8 to be cut off strip 14. Obviously, cutting device 31 is deactivated or eliminated when, as is often the case with transparent wrapping material, no end folds are required on portions 8. The leading end of strip 14 travels along the whole of forward branch 21 to transportation surface 49, which is coplanar with the outer surface of the portion of belts 17 extending along forward branch 21. The leading end of strip 14 reaches transportation surface 49 simultaneously with a pair of appendixes 47 which are engaged by a leading portion of strip 14 by virtue of the suction through holes 48. Conveyors 16 and 38, which are operated in steps and at the same speed, are stopped upon said pair of appendixes 47 reaching cutting station 54, and for as long as required for enabling cutting device 50 (as explained later) to perform a cutting operation, which, at least in this first case, is superfluous by virtue of the leading end of strip 14 being arrested facing the cutting edge of fixed blade 51. A further operating step of conveyor 38 feeds said pair of appendixes 47 up to the periphery of roller 40a, so that the leading end of strip 14 is drawn through transfer station 5 and into engagement with gumming devices 12, which provide for gumming given portions of surface 13 on the end portion of strip 14. When conveyor 38 stops, a further pair of appendixes 47, engaged by strip 14, is arrested in cutting station 54, at which point, strip 14 is cut between movable blade 52 and fixed blade 51. When cut, the end of strip 14 may become detached from appendixes 47 and adhere to the edge of fixed blade 51. Detaching member 55, in the gripping position, therefore retains strip 14 by suction and, by rotating anticlockwise into the operating position, detaches strip 14 from the edge of blade 51 so that it again adheres to respective pair of appendixes 47. At this point, a product 4, housed inside pocket 3 in station 5, is extracted from pocket 3 in a direction perpendicular to transportation surface 49, and fed between belts 45 and through spindle 57 into a corresponding seat 7 also located in station 5 and facing respective pocket 3. In the course of the above operation, product 4 engages and detaches portion 8 from respective appendixes 47, folds it in a U as it moves through spindle 57, and feeds it, so folded, into seat 7 so that two end portions (not shown) of portion 8 project from seat 7, and one of which is gummed on the side facing the other end portion. Folding devices 10 and 11 then fold the two end portions (not shown) one on top of the other, with the gummed end portion (not shown) on the outside, to produce a tubular wrapping (not shown) about product 4. Clearly, therefore, by virtue of the leading edge of strip 14 being drawn, as opposed to pushed, along transportation surface 49 and through station 5, no possibility exists of strip 14 curling as it travels through station 5 or, more especially, as it is detached from fixed blade 51. Moreover, the fact that each portion 8 is pushed through both the forward and return branches 36 and 37 of conveyor 38, and is gummed while on transportation surface 49 and on the side facing wheel 2, prevents any possibility of the gum on portion 8 fouling belts 45.

Claims: A method of feeding portions (8) of wrapping material to a wrapping machine (1), whereby the portions (8) having a first (13) and second surfaces opposite to each other are fed successively, by feeding and guide means (38) defining a transportation surface (49) for said portions (8), to a transfer station (5) wherein each portion (8) is positioned with its second surface facing a folding seat (7) so as to interfere with a respective product (4) which is moved through said feeding and guide means (38) and towards said folding seat (7) in a direction substantially perpendicular to said transportation surface (49); the portions (8) being drawn by the feeding and guide means (38) towards the transfer station (5); the feeding and guide means (38) comprising means (47) for gripping said portions (8), and transportation means (45) integral with said gripping means; characterized by the fact that said transportation means (45) are activated for bringing said gripping means (47) successively into engagement with said second surface of the portions (8), and so drawing the portions (8), via said gripping means (47), along the transportation surface (49) and through the transfer station (5). A method as claimed in Claim 1, characterized by the fact that each portion (8) is gummed on said first surface (13) which faces away from said seat (7) and while on said transportation surface. A method as claimed in Claim 1 or 2, characterized by the fact that said transportation means (45) comprise two looped belts (45) separated by a distance greater than the width of said portions (8) and comprising respective forward branches (36) moving towards the transfer station (5) and facing said second surface of said portions (8), and respective return branches (37) facing said seat (7); said gripping means (47) along said forward branches (36) defining said transportation surface (49); and each portion (8) being moved by a respective product (4) through both the forward (36) and return (37) branches of said belts (45) as it is inserted inside said seat (7). A method as claimed in any one of the foregoing Claims, characterized by the fact that the leading end of each portion (8) is engaged by said gripping means (47). A method as claimed in any one of the foregoing Claims, characterized by the fact that said portions (8) are drawn upwards towards said transfer station (5) by said feeding and guide means (38). A method as claimed in any one of the foregoing Claims, characterized by the fact that said portions (8) are formed from a continuous strip (14), the leading end of which is engaged by said feeding and guide means (38) and drawn towards said transfer station (5). A method as claimed in Claim 5, characterized by the fact that each said portion (8) corresponds with a leading portion of the strip (14), which, when located astride said transfer station (5), is cut off said strip (14). A device (9) for feeding portions (8) of wrapping material to a wrapping machine (1), the portions (8) having first (13) and second surfaces opposite to each other, and the device (9) comprising feeding and guide means (38) defining a transportation surface (49) for feeding the portions (8) to a transfer station (5) where each portion (8) is positioned, in use, with its second surface facing a folding seat (7) so as to interfere with a respective product (4) movable through said feeding and guide means (38) and towards said folding seat (7) in a direction substantially perpendicular to said transportation surface (49); the feeding and guide means (38) comprising means (47) for gripping said portions (8), and transportation means (45) integral with said gripping means (47); characterized by the fact that said transportation means are arranged so as to bring said gripping means (47) successively into engagement with said second surface of the portions (8), and so draw the portions (8), via said gripping means (47), along the transportation surface (49) and through the transfer station (5). A device as claimed in Claim 8, characterized by the fact that it further comprises gumming means (12) for gumming each portion (8) on said first surface (13), which faces away from said seat (7); said gumming means (12) being positioned, in use, facing said first surface (13) for gumming each said portion (8) while it is on said transportation surface (49). A device as claimed in Claim 8 or 9, characterized by the fact that said transportation means (45) comprise two parallel looped belts (45) separated by a distance greater than the width of said portions (8); said gripping means (47) being carried on said belts (45) and extending from each belt towards the other belt; said belts (45) comprising respective forward branches (36) moving towards the transfer station (5) and, in use, facing said second surface, and respective return branches (37) positionable facing said seat (7); said gripping means (47) defining, along said forward branches (36), said transportation surface (49). A device as claimed in any one of the foregoing Claims from 8 to 10, characterized by the fact that said transportation surface (49) is vertical; said gripping means (47) moving upwards along said transportation surface (49). A device as claimed in any one of the foregoing Claims from 8 to 11, characterized by the fact that it comprises a cutting device (50) located along said transportation surface (49), upstream from said transfer station (5), and on the opposite side of said transfer station (5) to said gumming means (12); the distance between said cutting device (50) and said gumming devices (12) being substantially equal to the length of said portions (8). A device as claimed in Claim 8 or 9, characterized by the fact that it comprises a first and second conveyor (16, 38) arranged in series and moving towards the transfer station (5) for feeding a leading portion of a continuous strip (14) of wrapping material through the transfer station (5) and along the transportation surface (49); the first conveyor (16) being a suction conveyor and being located upstream from the second conveyor (38); the second conveyor (38) defining said feeding and guide means (38) and being designed for assembly through said transfer station (5); and cutting means (50) being provided for cutting said leading portion off said strip (14) and so forming said portion (8). A device as claimed in any one of the foregoing Claims from 8 to 13, characterized by the fact that said gripping means comprise pairs of suction appendixes (47) located along said transportation surface (49) and separated by a distance smaller than the width of said portions (8).

Inventors: BORIANI SILVANO, MINARELLI ALESSANDRO, BORIANI, SILVANO, MINARELLI, ALESSANDRO
Applicants: GD SPA, G.D SOCIETA' PER AZIONI
Application year: 1992
Main classification: B65B41
IPC codes: B65B41, B65B11