Device for turning paper sheets into a desired orientation in a paper sheet folding machine

Abstract: A device for turning paper sheets to a desired orientation in a paper sheet folding machine which comprises an entraining system (14) for feeding a sheet to be folded and a side turning means engageable with and apt to cause the turning of said sheet in combination with the sheet entraining motion (18) thereof, wherein said side turning means comprises a wheel (20) which is rotatively driven to apply to the sheet (10) an entraining force in a direction (22) opposite to the direction (18) of the feeding motion applied to the sheet (10) by the entraining system (14). On a side of the system (14) entraining the sheet (10), a vertically movable abutment pin member (24) is provided for engaging an edge of the sheet (10) in order to stop the turning movement thereof in its lying plane, once the sheet (10) has reached a desired amount of turning.

Description: BACKGROUND OF THE INVENTION The present invention relates to a device for conferring a predetermined orientation to paper sheets, in particular drawing copy sheets,which are sequentially supplied to a paper sheet folding machine and must frequently be turned in their laying and feeding plane before being folded. As is known, the machines for automatically folding drawing sheets supplied by a reproduction or printing station are supplied with sheets of different size, which must be folded either one or more times in order to generally assume a standard sheet size, such as the A4 size. More specifically, the sheets being supplied to said sheet folding machine are fed on a sheet supporting table provided, in a per se known manner, at a central region thereof, with sheet entraining means including one or more endless belts or wheel members slightly protruding from the surface of said sheet supporting table. In order to turn a sheet which does not comply with the desired orientation, already known from DE 3048298 A is a system arranged between a drawing reproduction machine and a punching machine for perforating an edge portion of the drawing sheets for filing purposes, downstream of which a sheet folding machine can be arranged, said folding machine using a retaining pin which perforates and holds a portion of the sheet at a position thereof offset from the entraining means so as to apply to said sheet a turning torque for turning said sheet, as desired, about said retaining pointed pin, operating as a pivot pin. The above mentioned device is of a passive type since it constitutes a stationary point with respect to the sheet and does not affect the rotation speed of the sheet, the rotation thereof being caused only indirectly by its co-operation with the entraining belt movement. In addition, US 5 090 683 A, which corresponds to the preamble of claim 1, relates to a sheet rotation device comprising two drive rollers which normally are rotated at the same speed as the input and output rollers, causing the forward feeding of the sheet, and co-operate therewith in performing this forward motion. When the sheet is to be rotated of 90°, the speed of one of said drive rollers is varied, usually decreased, to cause the rotation of the sheet. SUMMARY OF THE INVENTION The aim of the present invention is to speed up the turning movement of sheets, requiring the above mentioned turning operation before being folded, by means of an active type of device based on a different construction principle which allows the sheets to be turned at a greater speed, said device being suitable for use with any size of sheets. This aim is achieved by a device according to claim 1. The sheet turning device comprises the provision of a single friction wheel peripherally coated by a material (for example a rubber material) apt to develop a sufficient friction on the paper material without damaging it, said friction wheel being driven by a small low power motor which rotates said wheel in a direction such as to apply to the sheet a tangential rotation force opposite to the feed direction of said sheet, caused by the underlying driving belts or wheels. The so obtained turning movement of the sheet is stopped when said sheet being fed in its displacing direction on a sheet supporting table has turned through a desired degree of rotation, as detected or set by suitable means known in the art. Alternatively, said turning movement can be stopped, according to the present invention, by abutment means whereagainst an edge of the sheet abuts, thereby providing an accurate orientation of the sheet. In this case, the abutment means, controlled by a sensor, is withdrawn from the table surface, with the simultaneous removal of the friction wheel from the sheet, thereby discontinuing the turning torque, in the table plane, generated by the entraining belt movement and the counter-rotation of the friction wheel. Under a combined action on the sheet developed by said driving belts operating underneath the sheet and by the counter-rotating friction wheel is obtained an angular turning speed of the sheet, depending on the turning speed of the friction wheel operating as an active element, greater than that attainable by a simple entraining motion of the driving belts with respect to a stationary point. In order to detect a precise position of the front or side edge of the sheet it would be possible to use, for example, sensors, photocells, timing circuits, digital encoder controllers, step-by-step motors; however, particularly for large size sheets, it is preferable to use one or more abutment elements, such as abutment pins, which interrupt, in a geometrically precise manner, the turning movement of the sheet, since the friction wheel could, for a short time, slip on the top surface of the sheet, allowing only the prosecution of the longitudinal entraining action on the sheets caused by the entraining belts towards the folding unit proper. The abutment element can be arranged either above or underneath the sheet supporting table and it is preferably driven by a magnetic coil operating against a return spring. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be disclosed hereinafter with reference to the accompanying drawings, wherein: Figure 1 schematically illustrates a sheet entraining system for entraining a sheet through a sheet folding machine and provided with a sheet turning device according to the present invention, for turning a sheet through 90°; Figure 2 illustrates said system, with the sheet being turned; Figure 3 illustrates said system after a 90° turn of the sheet; Figure 4 illustrates the system shown in Figure 3, comprising stopping means for safely stopping a sheet at a 90° turned position thereof; Figure 5 illustrates the sheet stopping means in its inoperative condition, before the actuation of said means for providing an accurate 90° turn of the sheet; and Figure 6 illustrates said stopping means in its active position, for ensuring an accurate 90° turn of the sheet. DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the present invention, a paper sheet 10 is arranged on a sheet supporting table 12 of a folding machine. Said sheet 10, depending on the size thereof, could require to be rotated through 90° for it to be oriented to the desired position in order to arrange the same sheet 10 to be folded to a UNI A4 size, irrespective of its starting size in its unfolded condition, so that, for example, a legenda/caption table on a sheet of drawing is oriented as desired. The paper sheet 10 is entrained on the table 12 by an entraining or feeding system 14 which can comprise either one or more endless loop belts 16 stretched on two opposite axles or rolls which cause the motion of the top portion of said belts, for example in a direction indicated by the arrow 18. The belts 16 can be replaced by one wheel or by a plurality of wheels aligned on one or more sliding axles, as it is known to those skilled in the art. If said sheet 10 is to be turned through 90°, which condition is detected in a conventional manner by suitable sensors detecting both the size and orientation of the sheet 10, then a single wheel 20, provided laterally of the entraining system 14, is lowered to contact the sheet 10 and it rotates so as to tend to drive the sheet 10 in a direction indicated by the arrow 22 opposite to the direction indicated by the arrow 18. Thus, the sheet 10, under the combined effect of two offset entraining forces, as shown by the arrows 18 and 22, will turn in its plane as long as the wheel 20 is held in contact with the sheet 10. Usually the wheel 20 which, for a proper operation, must have a peripheral portion thereof made of a high friction material, is arranged at a position raised from the sheet 10 and, at said position, it can also be retained in an inoperative (non rotating) condition. In its operative position, in which it has been lowered to contact the sheet 10, said wheel is rotatively driven by a low power small electric motor, turning with a low revolution number. An electric device lowers the wheel 20 onto the paper sliding surface for the short time necessary for causing the sheet 10 to be turned. The above mentioned lowering and raising movements, as well as the related operating times, will be controlled by any known controlling means not pertaining to the invention. The combined operation of the entraining system 14 and reversely-turning wheel 20, allows the sheet 10 to perform a combined movement of turning about its axis and of its displacement in a longitudinal direction. This combined movement will allow the sheets to be turned at a very high speed, even if they are of a large size and, consequently, without any limitations as to their minimum and maximum size. Of course it is clear that the rotation of the wheel 20 at an edge of the sheet 10 should be sufficient to cause the rotation of the sheet 10, but the combined motion of the wheel 20 and the sheet 10 being moved forwardly in a longitudinal direction opposite to the direction of rotation of the wheel 20 allows to accelerate the rotation of the sheet. The operation of said wheel 20 will be stopped as the sheet 10 arrives at a desired position, which need not necessarily be a 90° turning position. In this condition, the wheel 20 will be raised away from the sheet 10 and the rotary motion of said wheel will be stopped. In order to detect the final position assumed by the sheet 10, it is possible to rely on numerous already available detecting devices, not falling within the scope of the instant invention. Among these prior solutions, the most widely used devices are a photocell system, a timing circuit, a digital encoder controller or a step-by-step motor system. In order to ensure an accurate turn of the sheet 10 which is to be folded, the present invention provides for the use of a pin member 24 which can be arranged at a first inactive position, disengaged from the sheet 10, or at a second active position, engaged with said sheet 10. In its active position, the pin member 14 will operate as an abutment element whereagainst an edge of the sheet 10 will be abutted, thereby providing a precise orientation of the sheet 10 and precisely defining the moment in time in which the operation of the sheet turning wheel 20 should be stopped. A possible additional turning force applied to the sheet 10 will accordingly be discontinued, and this not only due to the stopping of the rotary movement of the wheel 20 and/or the disengagement of the latter from the sheet 10 but also to a slipping of the sheet 10 on the entraining system 14 and on the wheel 20 which might possibly still be in contact with the sheet 10. Thus, it is possible to provide a more accurate positioning, especially of-large size sheets for which, in particular, it could be advantageous to use several pin members 24 arranged along a side of the sheet 10. At the end of the turning movement of the sheet 10, the pin member 24 will be disengaged from the surface of the table 12, by raising said pin member from said table 12. It clearly ensues that if the pin member 24 were arranged underneath the table 14, instead of above it, then the operative condition of said pin member would be obtained by making it to protude the bearing surface of the sliding table 12, whereas the inoperative condition thereof would be provided by lowering it under said surface. The activating and disactivating of said abutment pin member 24, in the embodiment shown in Figures 5 and 6 respectively, is achieved by providing an electromagnet 26, in one of several possible embodiments thereof encompassing the pin member 24. The bottom portion of the pin member 24, provided for operating as a stop element for stopping the rotary movement of the sheet 10, engages the surface of the table 12 or, more advantageously, it will partially fit, as shown, into a hole 32 provided therein. The top portion of the pin member 24 projects from the electromagnet and is encompassed by a return spring 28 held at the top by a shoulder, for example a small plate 30 and, at the bottom, by said electromagnet 26. The energizing of the electromagnet 26 will preferably cause, as in the preferred embodiment shown, the pin member 24 to be lowered to its active condition shown in Figure 6, in opposition to the force of said spring 28, whereas the de-energizing of said electromagnet 26 will cause the spring 28 to restore said pin member 24 to its inactive position by raising it to the position shown in Figure 5. It is evident that the energizing of the electromagnet 26 could, alternatively, operate in the opposite way.

Claims: Device for turning paper sheets to a desired orientation in a paper sheet folding machine which comprises a sheet entraining system (14) for feeding a sheet to be folded and a single rotary wheel (20) for turning the sheet (10) which is arranged laterally of said sheet entraining system (14), characterised in that said wheel (20) rotates in a direction opposite to the direction of the feeding of said sheet caused by said entraining system (14), in that, when the turning of the sheet is requested, said wheel (20) is brought in contact with said sheet (10) by lowering and raising means and rotatively driven for applying to said sheet, at an edge thereof, an entraining force in a direction (22) opposite to the direction (18) of the feeding of said sheet caused by said entraining system (14), and in that said wheel (20) is disengaged from said sheet (10) by said lowering and raising means and the rotary movement thereof is stopped once said sheet (10) has undergone the desired turning movement. A device according to claim 1, characterised in that said wheel (20) is driven by a low revolution motor. A device according to claim 1, characterised in that said wheel (20) is coated with a high friction material. A device according one or more of the preceding claims, characterised in that an abutment pin member (24) is provided laterally of said sheet entraining system (14) for engaging an edge of said sheet (10) to prevent said sheet from further turning in its lying plane once said sheet (10) has reached the desired degree of turn. A device according to claim 4, characterised in that said pin member (24) is able to assume an active position in which said pin member forms a projection with respect to said laying plane of said sheet to accurately position said sheet at a desired orientation. A device according to claims 4 and 5, characterised in that said pin member (24) is driven by an electromagnet (26), encompassing said pin member (24), against a force generated by a return spring (28).

Inventors: RIGOLI VITTORIO, RIGOLI, VITTORIO
Applicants: RIGOLI F I M E S P A, RIGOLI F.I.M.E. S.P.A.
Application year: 1997
Main classification: B65H9
IPC codes: B65H9, B65H5