Centrally controlled automatic device for feeding single sheets or the like within a packaging machine

Abstract: A centrally controlled automatic device for feeding single sheets or the like in a machine for packaging signatures, newspapers or the like in a continuous film of thermoplastic material, comprising a frame, means for containing sheets stacked one on the other for feeding, means for separating at least one sheet (13) from the bottom of the container means (12), means for extracting at least one sheet (13) separated by the separation means, and means for evacuating at least one sheet (13) once extracted, wherein the extraction means consist of a lower conveyor band (17) on which a presser roller (27) is caused to engage with rocking movement, the rocking movement being provided by a first cam mechanism (37,38,39) which causes the presser roller (27) to move from a first detached position to a second position of engagement with the lower conveyor band (17) as soon as the separation means (43,44) have gripped an initial portion of the sheet (13) and moved it from the bottom of the container means (12) onto the lower conveyor band (17), there also being provided a second cam mechanism (45,46,47) arranged coaxially to the first cam mechanism (37,38,39) to operate the separation means (43,44), the first and second cam mechanisms (37,38,39; 45,46,47) being driven by a single central drive shaft (16), which rotates the extraction means.

Description: This invention relates to a centrally controlled automatic device for feeding single sheets or the like within a packaging machine. In known machines for packaging signatures, newspapers or the like in a continuous film of thermoplastic material, it is known to provide automatic devices for feeding single sheets or the like, which withdraw the single sheet from a container and feed it onto the continuous film of thermoplastic material, for example unwinding from a reel. Known sheet feeding devices are provided with means which separate one of the sheets disposed in the container, in particular that close to its base, and means which extract said sheet from the container and feed it onto a conveyor band which transfers it onto the continuous film. Said separation means are generally sucker devices, while the extraction means are grippers which grip the end portion of the sheet and pull it to move it onto the conveyor band. However, said grippers have difficulty in correctly gripping the sheet in phase with the speed of operation of the packaging machine. They can also tear the sheet due to incorrect gripping, or form drag marks or impressions at the gripping points. Moreover, because of their constructional complexity, they can also cause phasing problems for their constituent elements and are consequently subject to inconstant and imperfect operation. CH-A-475,095 relates to a device for feeding single sheets or the like in a machine for packaging signatures, newspapers according to the preamble of claim 1. DE-A-3,134,949 discloses a device provided with a second cam mechanism to operate separation means. An object of the present invention is to provide an automatic sheet feed device in which said extraction means are such as to overcome all the problems of synchronization and possible product damage inherent in known packaging machines. A further object is to provide a device with a single central drive for it and for all the further means which cooperate in its correct operation. These objects are attained according to the present invention by a centally controlled automatic device for feeding single sheets or the like in a machine for packaging signatures according to claim 1. In a preferred embodiment the conveyor band consists of a series of parallel accompanying belts which cooperate with at least one pair of drums of diameter greater than the support for the belts, so that advantageously the presser roller enters into engagement only with the pair of drums when the sheet withdrawn from the container means is interposed, so ensuring reliable operation in perfect synchronism with and preventing any damage to the gripped and extracted sheet. The structural and operational characteristics and advantages of a device according to the present invention will be more apparent from the description given hereinafter by way of non-limiting example with reference to the accompanying schematic drawings, in which: Figure 1 is a perspective view of the automatic feed device of the present invention, in which the container means for the sheets to be fed and portions of the device shoulders have been omitted; Figure 2 is an elevational view within a shoulder showing schematically the path of the belts, the drums associated with them and the presser roller which cooperates with them; and Figures 3, 4 and 5 are operating diagrams of the device of the present invention showing successive operating stages. In a packaging machine for signatures, newspapers or the like there is usually provided, particularly at its front, an automatic device for feeding single sheets or the like to be packaged in a continuous film of thermoplastic material, which is fed for example from a reel. An automatic feed device of the type according to the present invention is shown in the figures, in which all parts in common with known devices are omitted or shown only schematically. The automatic feed device for single sheets according to the invention comprises essentially a series of means arranged in a particular combination. Essentially they comprise means for containing the sheets stacked one on the other for feeding, means for separating at least one of said sheets from the bottom of the container means, means for extracting at least one sheet separated by the separation means, and finally means for evacuating the sheet. More specifically, the illustrated device comprises essentially a frame, represented schematically by the pair of shoulders 11, on the top of which a container means indicated overall by 12 is disposed, in which single sheets 13 or the like are stacked one on the other. In the lower part opposite the container means 12 there is an exit table represented schematically by 14 and consisting for example of a conveyor (not shown) on which a continuous film of thermoplastic material (also not shown) is fed, to be used for the packaging. A central drive means (not shown), of which only a motion transmission chain 15 deriving from it is shown, provides for the entire movement of all the parts of the device according to the invention. More precisely, the chain 15, engaged about a sprocket 20, rotates a central drive shaft 16 on which the sprocket 20 is keyed and which is supported between the shoulders 11 to firstly rotate a lower conveyor band consisting essentially of a first series of belts 17. In the illustrated example two belts 17 are shown purely by way of example and to allow better understanding of the drawing, but are usually more numerous. The belts 17 accompany each other spaced apart and parallel, and in their initial portion are positioned essentially below the container means 12. The belts 17 pass within recesses 18 provided in a pair of drums 19 rigid coaxially with the central drive shaft 16. In this manner the drums 19, which are of greater diameter than the recesses 18 and the portions of the belts 17 contained within them, enter into engagement with a presser roller 27 which is described in detail hereinafter. Beyond the region in which it is supported by that shoulder 11 opposite the one at which it receives its rotary motion, the drive shaft 16 carries a composite belt transmission by which it rotates a series of means which constitute the device of the invention. In this respect, a first toothed pulley 21 keyed onto the drive shaft 16 rotates a belt 22 provided with teeth on both its surfaces. The teeth on the outer surface of the belt 22 engage a second pulley 23 provided on a second shaft 24 and free to rotate on interposed bearings. The second pulley 23 is rigidly connected to a third pulley 25 of greater diameter, which is also free to rotate on interposed bearings and with which there engage a second toothed belt 26 to rotate a presser roller 27 and a third toothed belt 28 to rotate an upper presser band consisting of a second series of belts 29. The presser roller 27 and the first series of belts 17 essentially form the said extraction means for the sheet 13, the presence of the drums 19 completing or improving said extraction means in a preferred embodiment such as that described. The second series of belts 29 in cooperation with the terminal portion of the first series of belts 17 form said evacuation means for the sheet 13. It can be seen that a pair of levers 31 supporting the presser roller 27 are fixed on the second shaft 24 by end clamps 30. It can also be seen that an extension of one end of a shaft 32 connected to the roller 27 carries a further toothed pulley 33 which receives its motion from the second toothed belt 26, to rotate the roller 27. Because of the particular arrangement and rocking motion of the presser roller 27 which is explained hereinafter, the second toothed belt 26 is provided with a rotary tensioning device 34 rotatably supported on a right-angled lever 35 rigidly secured to one end of the second shaft 24 by a locking clamp 36. The device according to the invention is provided with a first cam mechanism which causes the presser roller to move from a first position detached from the first series of belts 17 or rather from the drums 19 to a second position in engagement with them. This first cam mechanism consists essentially of a first cam 37 keyed onto the drive shaft 16 and on which an elastically yieldable articulated lever system 38 acts to transform the rotational motion of the cam into rocking motion of an end lever 39 locked on the second shaft 24. In this manner the second shaft 24 is subjected to a rocking movement which is consequently transmitted to the presser roller 27 supported on it. An elastic element such as a spring 40 is secured at one end to the shoulder 11 and at its other end to a free end of a further lever 41 rigid with the free end of the second shaft 24. The spring 40 therefore exerts traction on the lever 41 which by rotating the second shaft 24 urges the presser roller in the direction against the first series of belts 17, ie against the drums 19. The device of the invention is also provided with means for separating the sheets 13 from the bottom of the container means 12. More specifically, in a position corresponding with an aperture 42 provided in the base of the container means 12 there is a series of sucker elements 43 supported on a third shaft 44 arranged transverse to the shoulders 11 and caused to rock by a second cam mechanism provided at one end. The structure and operation of the sucker elements is of known type, and the second cam mechanism comprises a second cam 45 keyed onto the drive shaft 16, and on which a further elastically yieldable articulated lever 46 system acts to transform the rotational motion into rocking motion of an end lever 47 locked on the third shaft 44. In this manner the third shaft is subjected to a rocking movement which causes the sucker elements 43 to move from a first retracted position below the conveyor band, ie below the first series of belts and below the outer surface of the drums, to a second position corresponding with the aperture 42 of the container means where they engage an initial portion of the sheet 13. Again in this case an elastic element such as a spring 48 is provided suitably secured at one end to the shoulder and at its other end to a further lever 49 of the articulated lever system 46 to ensure engagement of the sucker elements on the initial portion of the sheet 13. The operation of an automatic device according to the invention is to some extent apparent from the aforegoing description, but can be summarized as follows with particular reference to the diagrams of Figures 3 to 5. Thus in a first stage the two cam mechanisms 37, 38 and 45, 46 determine the position shown in Figure 3 in which the presser roller 27 is raised from the belts 17 and drums 19, and the suckers 43 are in contact with an initial portion of a sheet 13 at the aperture 42 in the container means 12. As the rotation of the second cam mechanism 45, 46 continues the suckers 43 rotate clockwise to drag the initial portion of the sheet 13 onto the drums 19 and belts 17 (Figure 4). It is only at this point that the first cam mechanism 37, 38 causes the presser roller to swing onto the initial portion of the sheet 13 to retain it between the presser roller and the outer surfaces of the drums 19 (Figure 5). At this point the suckers 43 disengage in known manner to allow the further rotation of the central drive shaft 16 to advance the sheet 13, which being supported only at the exit of the drums 19 on the belts 17 moves until it becomes inserted between the belts 17 and the belts 29 of the upper presser band. The cycle then continues with the further extraction of a sheet and its further feed onto the continuous film of thermoplastic material of the packaging machine. The particular structure of the centrally controlled automatic feed device of the present invention and its positive movement transmission ensure perfect synchronism between the various speeds by proper choice of the toothed pulley dimensions and cam contours based on the various transmission ratios required. This type of transmission also ensures correct transmission of rotation to the presser roller by virtue of having provided a rotary tensioning device which rocks rigidly with the rocking of the second drive shaft supporting the presser roller and which consequently maintains correct tensioning of the toothed belt in the various positions. The particular structure of the extraction means formed from the presser roller and the lower conveyor band and the further presence of the drums ensure reliable extraction of the sheet previously separated from the container means, and at the same time prevents any damage to the sheet.

Claims: A centrally controlled automatic device for feeding single sheets or the like in a machine for packaging signatures, newspapers or the like in a continuous film of thermoplastic material, comprising a frame (11), means (12) for containing sheets (13) stacked one on the other for feeding, means (43) for separating at least one of said sheets from the bottom of said container means (12), a lower conveyor band (17) on which a presser roller (27) is caused to engage with rocking movement for extracting said at least one sheet separated by said separation means (43), a first cam mechanism (37,38) to cause said presser roller (27) to move from a first detached position to a second position of engagement with said lower conveyor band (17) as soon as said separation means (43) have gripped an initial portion of said at least one sheet and moved it from the bottom of said container means (12) onto said lower conveyor band (17), and means (17,29) for evacuating said at least one sheet once extracted, characterised in that a second cam mechanism (45,46) arranged coaxially to said first cam mechanism (37,38) is provided to operate said separation means (43), said cam mechanisms (37,38 and 45,46) being driven by a single central drive shaft (16), which provides advancement of said lower conveyor band (17), and in that said presser roller (27) is positioned on levers (31), which rock about a second shaft (24), rigid with which there is provided a second lever (35) carrying a rotary tensioning device (34) for a presser roller drive belt (26) driven by means of a belt transmission (21-25) from said central drive shaft (16) to continuously rotate said presser roller (27) at a peripheral speed synchronous with the speed of advancement of said lower conveyor band (17).

Inventors: BALLESTRAZZI ARIS, TASSI LAMBERTO, BALLESTRAZZI, ARIS, TASSI, LAMBERTO
Applicants: SITMA SPA, SITMA S.P.A.
Application year: 1991
Main classification: B65H3
IPC codes: B65B41, B65H3