Abstract:
A method of and an apparatus for feeding a processing machine with flat products, such as printed sheets, cards, patterns or the like. Over a conveyor path arranged between a storage unit and the processing machine and forming a product storage unit, the flat products are carried from the storage unit in a stream formed by products arranged in an overlapping configuration. The product stream conveyed on the conveyor path toward the processing machine is followed by a product stream having a higher speed. The apparatus includes a device with a drivable storage unit for removing the flat products, wherein the storage unit is connected through a conveyor unit to a processing machine for processing the products. The conveyor unit includes a plurality of separate conveyor elements arranged one behind the other and driven in the same direction, wherein a sensor each is directed to the conveying ends of the conveyor elements, and wherein each sensor is connected to a control unit for changing the discharge speed of the product from the storage unit and/or the conveying speed of the products on the conveyor elements.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a method of feeding a processing machine with flat products, such as printed sheets, cards, patterns or the like. Over a conveyor path arranged between a storage unit and the processing machine and forming a product storage unit, the flat products are carried from the storage unit in a stream formed by products arranged in an overlapping configuration. 
     The present invention also relates to an apparatus for carrying out the method. 
     2. Description of the Related Art 
     It is known in the art to wind printed products delivered by printing machines or folding machines in a stream formation onto a roll core and to subject them to intermediate storage, so that they can be further processed at a later time. 
     In a processing machine for such printed products, for example, a gather stitcher or saddle stitcher, the printed products rolled up in the stream formation are again unwound for feeding the gather stitcher in an unwinding station and for transporting the printed products over a relatively short conveyor path to the processing machine, wherein the printed products may have to be turned into a processing position. Single-roller or double-roller stations are available for this purpose. 
     The single-roller station, which includes one roll, is less expensive and requires less space, however, the station makes it necessary to interrupt the processing machine or gather stitcher when an empty roll core has to be replaced by a new roll. For this reason, the processing machine cannot be utilized in an optimum manner and processing is to a certain extent unproductive. 
     The double-roller station avoids this disadvantage by making it possible, when a roll is empty, to immediately switch through a switch to a roll which has been prepared in an adjacent area. 
     However, double-roller stations are expensive and require more space which frequently is not available. 
     SUMMARY OF THE INVENTION 
     Therefore, it is the primary object of the present invention to further develop a method and an apparatus of the above-described type in which the disadvantages of the use of a single-roller or double-roller are avoided and the advantages are maintained. 
     In accordance with the present invention, the product stream conveyed on the conveyor path toward the processing machine is followed by a product stream having a higher speed. 
     The present invention makes it possible in a simple manner and without harmful effects for the further processing to prevent any difficulties which may be caused by an exchange of a roll of a single-roller station or any other problems which may lead to an interruption of the supply of products at the storage unit or the conveyor path. In other words, it is made possible in a simple manner and without any damage to the further processing to prevent interruptions in the supply of the products. 
     Moreover, the present invention makes it possible to obtain sufficient time for an exchange of a full roll against an empty roll core to be removed from the rolling station or when an unforeseen interruption occurs in the feeding path of the products to the processing machine; when the roll is to be exchanged, a residual amount of products still present on the roll is fed at a higher speed than the product flow already on the conveyor path, so that the subsequent products form on the conveyor path a more dense product stream; in the event of an interruption in the feeding path, the resulting gap can be at least essentially closed by the subsequently fed product stream in order to be able to maintain the continuity of processing. 
     The apparatus for carrying out the method according to the present invention includes a device with a drivable storage unit for removing the flat products, wherein the storage unit is connected through a conveyor unit to a processing machine for processing the products. The conveyor unit includes a plurality of separate conveyor elements arranged one behind the other and driven in the same direction, wherein a sensor each is directed to the conveying ends of the conveyor elements, and wherein each sensor is connected to a control unit for changing the discharge speed of the product from the storage unit and/or the conveying speed of the products on the conveyor elements. 
     The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     In the drawing: 
     FIG. 1 is a schematic side view of an apparatus according to the present invention; 
     FIG. 2 is a side view, on a larger scale, of a portion of the apparatus of FIG. 1; 
     FIGS. 3-6 are simplified illustrations, on a smaller scale, showing the apparatus in various phases of operation; and 
     FIG. 7 is a block diagram. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIGS. 1 and 2 of the drawing show an apparatus  1  according to the present invention for feeding a processing machine  2 . The processing machine  2  may be, for example, a gathering machine. The drawing shows of the gathering machine a channel-like gathering unit  5  and a stacking magazine  4  belonging to a known feeder  3  and being fed with printed sheets  6 . 
     The printed sheets  6  are made available for processing in a storage unit in the form of a roll  12  and, as also shown in the drawing, are conveyed to the processing machine  12 . The roll  12  has a core  7  which is rotatably mounted in a support  8 . The layers of the printed sheets  6  present as a stream formation and wound around the core  7  are held on the core  7  by means of winding belts  9 , wherein one end of each winding belt  9  is attached to the core  7  and the other end is attached to the roller  11  supported in a belt magazine  10 . 
     Contrary to the illustration in FIG. 1, the belt magazine  10  is mounted on the support or frame  8  and the roller  11  is coupled corresponding to the roll  12  with the drive shaft of a gear motor 
     For conveying the printed products, the processing machine  2  and the roll  12  are connected through a conveyor unit  13 , so that when the stream of printed products  6  is unrolled from the roll  12 , the printed products reach the first conveyor element  14  as seen in conveying direction, i.e., the first conveyor element  14  of the conveyor elements  14  to  18  forming the conveyor unit  13 . The roll  12  may be driven at the axis of the roll core  7 , or, as shown in the drawing, with a conveyor belt  19  at its periphery. 
     Provided for conveying the printed products  6  from the roller  12  are the conveyor belts  19 - 21  which are usually used for feeding the processing machine  2  directly. The first conveyor belt  19  as seen in conveying direction is placed against the periphery of the roll by means of a lifting element  23  acting on an arm  22 . The roll is emptied by means of the driven conveyor belt  19  onto the subsequently arranged conveyor belts  20 ,  21  which are hinged to the arm  22  in such a way that an unimpeded conveying stream can be produced. The arm  22 , in turn, is pivotably mounted on a support  23 . A sensor F 8  produces a signal when the arm  22  has been lifted to such an extent that the supply of printed products on the roll has been emptied with the exception of a residual quantity. 
     The printed sheets  6  arriving from the roll  12  are conveyed from the conveyor belt  21  onto the conveyor element  14  which forms the entry of the product storage unit or conveyor unit  13 . Prior to reaching the conveyor element  14 , the printed sheets  6  may be turned. The product storage unit illustrated in the drawing is composed of five storage sections or conveyor elements  14 - 18  arranged one behind the other and, for reasons of space, on top of one another. 
     With the exception of the last conveyor element  18  which extends in a flat conveying plane, the conveyor elements  14 - 17  are constructed so that the printed sheets  6  are turned at the conveyor end by a deflection. The conveyor elements  14 - 17  are essentially of equal construction and operate in the same manner, but are driven so as to be individually and commonly controllable. 
     The conveyor elements  14 - 17  are formed by two laterally offset endless belts  24 ,  25  and a guide roller  26  as well as several deflection rollers  27 , wherein the belts travel around the rollers so as to form a support for the printed sheets  6 . The conveyor elements  14 - 17  of the illustrated embodiment each have a long flat section and a subsequent essentially circular curved section on which the printed sheets  6  are transported, wherein the flat section is formed by two deflection rollers  27 ,  27 ′ and the bottom portion of the guide roller  26 . The upwardly directed circular section on which the printed sheets  6  are transported is formed inwardly by the guide roller  6  and outwardly by the circular belts  24 ,  25 , wherein the belts  24 ,  25  subsequently are returned about a guide roller  28  and a deflection roller  27  to the deflection roller  27 ′ so as to form the conveyor end at the flat section of the conveyor element  14 . 
     The end of the conveyor element  14  is followed by the flat section of the second conveyor element  15 . The end of the conveyor elements  13  forms the flat conveyor element  18  which is formed of two spaced-apart belts  24 ,  25  travelling around the deflection rollers  27 . 
     Of course, the longer flat section of a conveyor element  14 - 18  could in conveying direction of the printed sheet  6  also be arranged following the curved section, which would mean that the first conveyor element  14  would approximately correspond to the illustrated conveyor element  18 . 
     A conveyor belt  29  is provided as a transition from the conveyor unit  13  to the stacking magazine  4 , as illustrated in FIGS. 1 and 2. The printed sheets  6  conveyed on the conveyor belt  29  are taken over by an accelerating unit  30 . 
     The conveyor belt  29  is also driven by a separate motor M B . 
     The drive of the conveyor elements  14 - 18  can be effected by controllable electric motors M 1  to M 5  for individual conveyor elements or for several conveyor elements  14 - 18 , wherein the electric motors each act on a guide roller  26  or deflection roller  27  of a conveyor element  14 - 18 . 
     In accordance with an advantageous feature, always one of the deflection rollers  27  of a conveyor element  14 - 17  supporting the belts  24 ,  25  is constructed so as to be resilient, so that streams of printed products having different thicknesses can pass the curved sections of the conveyor elements  14 - 17 . 
     FIG. 2 shows additional features of the embodiment of the apparatus according to the present invention shown in FIG. 1; these additional features will be described below. 
     When the conveyor unit  13  has an odd number of deflections, the conveyor unit  13  can be used as a turning unit for changing the position of the printed sheets. 
     A sensor F 1  to F 6  each is arranged at the upstream ends of the conveyor elements  14 - 18 . An additional analog sensor F 7 , for example, a level sensor, is arranged at the machine  2 . The sensor F 7  controls the motors M 1  to M 5  and M R  in such a way that during normal operation the winding belt  9 , all conveyor belts  19 - 21  and the conveyor elements  14 - 18  as well as the conveyor belt  29  have the same speed which is such that the machine  2  can reliably process the supplied stream  31  of printed products. 
     FIG. 7 shows an embodiment of the control unit  40  for controlling the motors M. The sensor F 7  controls a first frequency transformer FU 1  whose frequency during normal operation drives all motors M 1 -M 5 M R , M B . 
     The signal of the sensor is also connected to two additional frequency transformers FU R  and FU 2  through two multipliers  41 ,  42  which multiply the signal by an adjustable factor each. For example, the frequency of these transformers is higher by a factor of five than the frequency of the transformer FU 1 . As a function of the signals of the sensors F 1 -F 8  and a starting signal, the motors M R , M B  and M 1 -M 4  are fed through a circuit  44 - 49  each either with the frequency of the transformer FU 1  or with the frequency of one of the transformers FU R  or FU 2 . 
     The operation of the apparatus  1  will now be described with the aid of FIGS. 3-6. FIG. 3 shows the normal operation in which all belts travel at the same speed as controlled by the sensor F 7 . The circuits  44 - 49  connect all motors M to the transformer FU 1 . The stream  31  has the same thickness over its entire length. 
     FIG. 4 shows the situation shortly before the end of the supply of products on the roll core  7 . For preparing a roll exchange F 8  has responded and switched the circuit  44 , so that the motor M R  and with it the motors of the belts  19 - 21  travel, for example, at five times the speed of the remaining belts. Beginning with the lowermost conveyor element  14 , a stream  31  is now formed on the conveyor elements  14 - 18  which has a greater thickness than was the case previously during normal operation. All conveyor elements  14 - 18  are ideally filled with the thicker stream  31 ′ when the roll core  7  is empty, as shown in FIG.  5 . 
     The sensor F 1  now determines the end of the stream  31 ′, switches the motor M R  through the circuit  44  and starts the roll exchange. 
     As soon as the thicker stream  31 ′ has reached the sensor F 6 , the F 6  switches through the circuit  49  the motor MB to a higher speed, so that the thickness of the stream  31 ′ can be reduced by spreading the printed sheets  6 . Since the feeding speed to the stacking magazine is increased, the sensor F 7  controls the transformers FU 1 , FU 2 , FU R  down by about the same factor, so that the conveyor belt  29  subsequently again travels with the original speed, while the conveyor elements  14 - 18  travel at a slower speed. 
     When the end of the thick stream  31  reaches each sensor F 2 -F 5  at the downstream end of the conveyor elements  14 - 17 , the sensors F 2 -F 5  successively switch the respective motors M 1 -M 4  through the circuits  45 - 48  to the higher frequency of the transformer FU 2 . 
     As soon as a new roll  12  has been inserted with its support  6  and the arm  22  has again reached the initial position shown in FIG. 1, the motor M R  is connected through a starting signal to the circuit  44  with the transformer FU R . Accordingly, the belts  9  and  19 - 21  travel at a higher speed than at least the last conveyor element  18 . 
     Through a logical circuit  20  in which the signals F 1 -F 6  are linked, all circuits  44 - 48  are returned through a reset input R back into their basic positions as soon as the new thinner stream  31  travels onto a conveyor element  14 - 18  on which the thicker stream  31 ′ is still present. This logical requirement is such that the circuit  50  produces a reset signal when one of the sensors F 1 -F 4  is switched off when the new stream  31  enters before the next following sensor F 2 -F 5  has been switched on because the thicker stream  31  has left. 
     When the end of the thicker stream  31 ′ passes the sensor F 6 , the sensor F 6  again switches off, so that the motor M B  is once again connected through the monostable circuit  49  to the transformer FU 1  and, consequently, travels at a slower speed. Immediately subsequently, the sensor F 7  will respond and the frequency of all transformers will once again be increased toward the original value. 
     The new thin stream now follows the exiting old stream with only a very small intermediate space which, as a rule, is smaller than the length of a conveyor element  14 - 18 . This makes it possible that the processing machine  2  can be operated practically without interruption during a roll exchange. The conveyor unit  13  or the product storage unit requires a small space and, most importantly, requires no additional space toward the sides, so that it can be easily integrated in existing plants where the available space is limited. 
     The sensor F 6  can also be constructed in such a way that it not only is able to discriminate between thin and thick streams  31 ,  31 ′ or between the thick stream  31 ′ and zero, but additionally between the thin stream  31  and zero. In that case, the control unit  40  according to FIG. 7 can be modified in such a way that the last conveyor element  18  can also be switched between the two speeds. In this connection, it is possible to connect all motors except M B  once again to the transformer FU 2  as soon as the end of the thicker stream  31 ′ has passed the sensor F 6 . The motors M 1 -M 5  and M R  are then once again switched back to the transformer FU 1  when the beginning of the new stream  31  reaches the sensor F 6 . This makes it possible to keep the interruption of the product stream to the machine  31  extremely short during the roll exchange or any other interruption of the supply. 
     The invention is not limited by the embodiments described above which are presented as examples only but can be modified in various ways within the scope of protection defined by the appended patent claims.