IMPROVED UNWINDING DEVICE FOR PAPER REELS

Abstract: For the discharge and the substitution of paper reels in devices for the unwinding of paper reels operating by contact with friction between the outer surface of the reel (34) and the upper reaches of endless friction belts (12a, b, c, d) a wedge-like member (36) is provided adapted to push the reel (34) to be discharged towards the upstream end of the unwinding device, the wedge-like member (36) being more and more wedged in between the belts (12a, b, c, d) and the reels (34) by operating the belts (12a, b, c, d) in a translation direction (F1) opposite to that of normal unwinding (F) of the paper band (C) from the reel (34). Moreover, sensing means (128, 130, 136) in form of a reflecting photocell are mounted at the downstream end of the unwinding device: the light ray (132) emitted from said photocell is intercepted from said reel (34) up to a predetermined height or diameter of the reel (34), whereby, when for a predetermined time the reflected ray (134) is lacking, a signal is generated from the photocell by which the translation motion of said belts is stopped.

Description: "Improved unwinding device for paper reels" The present invention relates to improved unwinding devices for paper reels, more particularly improved unwinding devices used for the paper reels feeding the fast printing machines, for instance laser printers, used for data processing centers such as the electronic accounting centers of banks and like institutions. The subject reels are of very remarkable weight, of the order of hundreds kilograms, whereby their unwinding and their handling raise not negligible problems. For example in the case of the feeding of laser printers the unwinding must necessarily take place at a constant, predetermined and adjustable speed, care being taken of the fact that the unwinding device is effectively servoed to the printer requirements. In the European Patent Application EP-A-384,533 in the name of the same Applicant an unwinding device is described which permits the unwinding of the continuous paper band from a reel to take place without it being necessary to support the reel onto a motorized mandrel and without the need of complex devices for the control of the reel diameter and of a consequent calibrated variation of the rotation speed of the unwinding mandrel, so as to ensure that the unwinding speed is constant. Such a result is achieved by an unwinding device essentially comprising a number of parallel and endless belts, which are motor driven thus effecting a translation motion so that their upper or operating reach forms a loop into which the reel to be unwound is abutting and seated. The material forming the belts has a sufficient friction coefficient towards the paper, whereby the combined action of the reel weight and of the translation motion of the belts causes the paper band to be unwound from the reel so as it comes out tangentially from the reel and parallelly to the translation direction of the belts. However, among the operating possibilities, also that requiring the substitution of the reel before it is exhausted exists, for example when it is necessary to change the size or the colour of the paper band, or because the paper band has defects such as to hinder the printing by the fast printer. Lacking other means, the substitution must be carried out manually, whereby the attendants must stop the unwinding device and thus the translation motion of the belts, cut the paper band and cause the reel to roll out of the aforesaid loop, possibly with the help of temporary reel lifting means. It is evident that such a proceeding has drawbacks not only from the point of view of the not negligible efforts for the carrying out of the substitution owing to the reel weight, but also and mainly from that of the dead times: if account is taken of the fact that the operating speed of a laser printer is of the order of 80 cm./sec, it is self-evident that the time of some minutes at least requested for the reel substitution is untolerable from the point of view of the production rate of the whole processing and printing line. In the copending Italian Patent Application No.MI91A002141, filed on July 31, 1991, in the name of the same Applicant, a method and a device are disclosed for the carrying out of the above mentioned operation, by which the above mentioned problem is solved limitedly to the case in which the reel to be substituted has still a rather high diameter and thus the reel weight is essentially close to that of the starting reel, whereas problems still exist in the case that the reels to be substituted are already mostly unwound and are thus of reduced weight. As a matter of fact, since according to the solution foreseen in this patent Application the discharge of the reel to be substituted takes place by means of a possibly prismatic roller which is pushed by the translation motion of the belts against the reel and in turn pushes the reel until it comes out of the loop formed by the unwinding belts, it may happen that the reel to be substituted steps over the pushing roller falling back into the loop formed by the unwinding belts. Another problem of the prior devices is that the weight of the reel close to the exhaustion becomes insufficient to ensure that the unwinding operation takes place correctly, whereby it must be substituted for by a novel full reel. As a matter of fact the unwinding is depending on the weight of the reel and thus on the force applied by the reel onto the belts. By the way the substitution of the reel must take place before the weight insufficiency of the reel does interfere with the correct operation of the unwinding device and thus with the feeding to the printer under predetermined speed parameters. The purpose of the present invention is that of essentially doing away with the problems and drawbacks as above shortly mentioned and particularly: (a) provide simple and reliable means for the ready and effortless substitution of a reel being unwound in an unwinding device of the type described in the above mentioned European Application, and (b) provide means likewise simple and operatively reliable to control the stopping of the unwinding device when the height or the diameter of the reel being unwound diminishes below a predetermined value. The device according to the present invention, of the type useful in a method and device in which, after the translation direction of the unwinding belts has been inverted, a stopping member is positioned upstream of the reel to be substituted so that the translation motion of the belts, by acting by friction on the reel, progressively pushes the latter out of the loop formed by said belts, the reel being prevented from falling back into said loop owing to the said stopping member, is characterized in that said stopping member consists of a wedge-like member having the upper inclined surface provided to come into contact with the outer surface of the reel to be substituted, whereas the lower surface is placed into contact for the friction dragging with the upper surface of at least one unwinding belt. Without imposing undue limitations to the present invention, it is worth to note that the combination of the dragging by friction of the wedge-like member with the tendency of the reel to be substituted to fall back when it starts the displacement from said loop and the climbing of the even short inclined flank of the exit side of said loop causes the wedge-like member to be more and more wedged in between reel and belts, whereby the weight of the reel cooperates in ensuring the engagement between the reel and the wedge-like member, thus being in opposition to the possible jumping of the reel with the related falling back into the afore said loop. According to another feature of the present invention the device of the invention is characterized in that at the exit end of the unwinding device means are provided sensing the height of the reel being unwound, said sensing means having connected thereto means for stopping the operation of the unwinding device in order to permit a novel paper reel to be charged within the loop formed by the unwinding belts when the height or diameter of the reel diminishes below a predetermined value. The specific features and advantages of the present invention shall more clearly appear from the following detailed description of the preferred embodiments with reference to the accompanying drawings, in which: fig.l is a side elevation, partially cross sectioned, view of the unwinding device of the invention in the normal operating condition; fig.2 is a view like fig.l in the condition of discharge of the reel being unwound; fig.3 is a plan view from above referred to fig.2; fig.4 is a perspective view of the wedge-like member used according to the present invention; figs.5 and 6 are views like fig.l and fig.3 respectively, showing another feature of the device according to the present invention. Referring firstly to fig.l there is shown the unwinding device comprising a frame 10 within which a number of belts is positioned, indicated by the references 12 (a,b,c and d), of the endless type and mounted onto two end shafts or rollers 14 and 16, having secured thereto, for example by keying, sleeves 18 (a,b,c and d) and 20 (a,b,c, and d), the above identified belts being engaged therewith. The sleeves 18 and 20 are preferably toothed and the belts 12 are correspondingly toothed in order to avoid any slipping between belt and sleeve from occurring. Either roller, in fig.2 the roller 20, is driven into rotation by a motor 22, possibly by interposing a variomotor or a gearmotor, whereas the roller 18 is idly mounted and serves as a mere return roller. The reference 24 indicates a control member of traditional type for the operation of the motor 22. The side bars 26 and 28, mounted onto supports generically indicated by the references 30 and 32, serve to maintain the reel 34 into alignement with the translation direction of the belts 12 indicated by the arrow F; of course at least one of the supports 30 and 32 is crosswise adjustable so as to permit the adjustment according to the width of the reel and thus of the paper band from which it is formed. The upper reach of the belts 12 forms a loop indicated by the reference A and by the arrow in fig.l, in which the reel 34 is placed; the paper band C is unwound from the reel 34 and advanced in the direction of the arrow F by the friction effect between the upper surface of the belts 12 and the outer surface of the reel 34. The advancement speed of the paper band C depends on the translation speed of the belts 12 and thus on the speed at which the roller 16 is driven by the motor 22. It is worth to note that the motor 22 is of reversible type namely rotatable in both directions and it can be controlled by per se known control means so as to adjust the rpm thereof as a function for example of the requirements of the downstream positioned laser printer. When it is desired to substitute the reel 34 with another one which for instance is of different size, namely having different width of the band from which it is formed, the motor 22 is stopped and the paper band is torn off downstream of the unwinding device. Then the wedge-like member 34, more detailedly shown in fig.4 and described hereinafter, is positioned between the upper surface of the belts 12 and the outer surface of the reel 34 to be substituted. Thereupon the motor 22 is operated again in the opposite direction, namely in that indicated by the arrow F, , whereby the wedge-like member is progressively wedged in between the belts 12 and the outer surface of the reel 34, and the latter is progressively pushed towards the upstream end namely the left one viewing fig.2, so that the reel 34 steps over the short inclined side defining the loop A and then is able to come out of the frame 10, thus making the unwinding device available to receive the novel desired reel. At that time it is enough to remove the wedge-like member 36 and operate again the motor 22 in the direction of the arrow F of fig. l , after having inserted the free end of the paper band of the novel reel at the inlet of the downstream positioned laser printer. Referring now to fig.4, the wedge-like member 36 consists of a block 38 having a base 40, either planar or suitably curved (the curvature being not shown in the figure) so as to match the slight curvature of the belts 12 in the area of the loop A. The operating part of the block 38 has a concave portion 42 which is joined to the base 40 so as to define a wedge-like member, the edge 44 of which shall have height as much as possible reduced, consistently with the requirements of mechanical strenght and particularly with the requirement of preventing any warping each time it is used, owing to the relevant weight of the reels 34. At the rear part the block 38 has a suitably inclined surface to permit a handle 46 to be provided. The wedge-like member has been described with reference to a preferred embodiment thereof, it being meant that mechanically and functionally equivalent modifications are possible and foreseable without coming out of the scope of the present invention. More particularly it seems necessary that the wedge-like member maintains the shape defined by the surfaces 40 and 42, whereas no particular requisites exist as regards the remaining parts of the member 36. Considering now the figures 5 and 6, the situation is shown of the case in which the reel 34 is close to the exhaustion thereof; at that time the weight thereof is no longer sufficient to keep it in the illustrated position and the unwinding of the paper band C therefrom is no longer permitted. According to the present invention downstream of the roller 16 an upright 126 is provided having at the upper end thereof sensing means 128, which in this embodiment consist of a reflecting photocell which is per se known. Preferably the height of the upright 126 is selected in such a manner that the photocell 128 is capable of sending through an emitter 130 a light ray 132 in a direction suitable to be intercepted by the reel 34 and by the paper present thereonto, giving place to the forming of a reflected ray 134 which is directed to the receiver 136 of the photocell 128. When the diameter of the reel is reduced to a value such that the ray 132 is no longer intercepted and thus the reflected ray 134 is no longer generated or when the receiver 136 is no longer receiving the reflected ray for a predetermined time (so as to avoid spurious influences due to oscillations of the reel 34 when it is close to its exhaustion) a control signal is generated from the photocell 128 whereby on one side in a per se known manner the motor 22 is stopped and on the other side the signal is transmitted to the downstream positioned printer so that the latter is stopped. As it is clearly shown in fig.6, the photocell 128 is oriented so that the light ray 132 is crosswise or diagonally directed with respect to the rectangle representing in plan the reel 34 so as to ensure the intercepting of the light ray 132 by the reel 34. In this case too conceptually and mechanically equivalent modifications are possible and foreseable for the skilled artisan.

Claims: CLAIMS 1. A device for the discharge and substitution of paper reels, of the type useful in a method and device for the unwinding of paper reels (34) comprising a number of endless belts (12) into friction contact with the outer surface of the outer surface of the reel to be unwound positioned in turn in a loop (A) formed by the upper reaches of said belts (12), in which, after the translation direction of the unwinding belts has been inverted, a stopping member (36) is positioned upstream of the reel (34) to be substituted so that the translation motion of the belts (12), by acting by friction on the reel, progressively pushes the latter out of the loop formed by said belts, the reel being prevented from falling back into said loop owing to the said stopping member, characterized in that said stopping member (36) consists of a wedge-like member having the upper inclined surface (42) provided to come into contact with the outer surface of the reel to be substituted, whereas the lower surface (40) is placed into contact for the friction dragging with the upper surface of at least one unwinding belt (12). 2. A device according to claim 1 , characterized in that said upper inclined surface (42) is a concave surface having a curvature suitable for matching the outer surface of the paper reel (34) to be substituted and said lower surface (40) has a slight curvature with the convexity outwardly directed. 3. A device according to claim 2, characterized in that said upper surface and said lower surface converge to a common wedging in edge (44). 4. A device according to claim 1 , characterized in that at the exit end of the paper band (C) from the unwinding device means (128,130,136) are provided sensing the height of the reel (34) being unwound, said sensing means having connected thereto means for stopping the operation of the unwinding device in order to permit a novel paper reel to be charged within the loop (A) formed by the unwinding belts (12) when the height or diameter of the reel (34) diminishes below a predetermined value. 5. A device according to claim 4, characterized in that said sensing means consist of a reflection photocell comprising an emitter (128) suitable to send a light ray (132) in a direction such as to intercept said paper reel (34) and a receiver (136) adapted to receive the reflected ray (134) generated by said light ray (132) impinging against the outer surface of said paper reel (34), said reflexion photocell being mounted at the upper end of a vertical upright (126), positioned at the downstream end of said belts (12) with reference to the direction of the the translation motion of the belts, said vertical upright having a height such that said photocell is positioned at a height that the emitted light ray is intercepted by the paper reel when the latter has a height or diameter greater than a predetermined value. 6. A device according to claim 5, characterized in that said reflecting photocell (130,136) is positioned so that the emitted light ray (132) is essentially directed according to a diagonal of the rectangle representing in a plan view the paper reel (34). 7. A device according to claim 5, characterized in that said photocell (130,136) is programmed so that when a predetermined time is elapsed without said receiver receiving said reflected ray, the photocell emits an electrical signal causing the motor means (22) driving said at least one belt (12) to be stopped. 8. A device according to claim 7, characterized in that said signal is also directed to the printer fed by the paper band (C) unwound from said reel.

Inventors: MESCHI LUCIANO, MESCHI, LUCIANO
Applicants: MESCHI IND GRAFICA, INDUSTRIA GRAFICA MESCHI SRL
Application year: 1992
Main classification: B65H26
IPC codes: B65H16, B65H18, B65H19, B65H26