Abstract:
Newspapers and other printed matter fed from a printing press or inserting machine are generally folded or delivered in a continuous stream with the papers oriented in an overlapped or imbricated relationship. The stream of papers are received and stacked by the stacking apparatus or stacker which must operate at high speeds. The stacker orients the papers in the stacks and ejects the bundles of papers. The present invention relates to devices intended to reduce the prospects for inadvertent interference with the stacking mechanism or to reduce the potential for injury.

Description:
This application claims priority from Provisional application U.S. Ser. No. 60/169,555, filed Dec. 8, 1999. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to the field of article stacking devices, and more particularly to stacking devices for assembling a stream of printed products into stacks or bundles and ejecting the stacks of printed products. Specifically, the present invention relates to devices intended to reduce the prospects for inadvertent interference with the stacking mechanism or to reduce the potential for injury. 
     2. Discussion of the Art 
     Newspapers and other printed matter fed from a printing press or inserting machine are generally folded or delivered in a continuous stream with the papers oriented in an overlapped or imbricated relationship. The stream of papers are received and stacked by the stacking apparatus or stacker which must operate at high speeds. The stacker orients the papers in the stacks and ejects the bundles of papers in at least two directions at a rate which exceeds one stack ejected per second. 
     Stackers generally operate by moving a fork into the continuous stream of papers to collect a desired number of papers which form a portion of the bundle. Forks are generally spring-mounted to a chain drive which rotates to continually receive and deliver batches of papers to a bucket or stacking section of the stacker. After a predetermined count of papers are received on a fork, a next fork intercepts the paper stream and begins collecting papers for the next batch. The forks move downward as the papers are collected and drop the completed batches onto a turntable which collects the papers in a stack. 
     Since newspapers and other printed materials generally have a thickness which is greater along the folded side of the paper than on the unfolded side of the paper, two or more batches are generally stacked on the turntable with the folded edges of the successive batches rotated 180° to form a bundle. This provides a more even stacking of the papers. In order to form the bundle with the alternately rotated batches, the stacking platform or turntable is driven by a heavy-duty motor which rotates the turntable 180° between receiving successive batches from the forks. 
     Once a predetermined bundle size is reached, the bundle is ejected from the stacker by, for example, pushing the bundle off the turntable with a pusher bar. Thus, the bucket area or stacking region where the bundles are formed on the turntable is a complex mechanical region where a number of moving components are operating very rapidly to keep up with the demands of the printing press. For example, printed products are dropped from overhead. The turntable undergoes periodic rotation. The bundle eject mechanism is periodically operated to remove the bundle from the turntable. Accordingly, this region has been maintained at least partially open to allow access to the various components and provide ease of maintenance access. However, in an effort to preclude interference with this complex mechanical operation, and also to reduce the possibility for potential injury, improvements to the stacker are desired. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an elevational view of a conventional stacker. 
     FIG. 2 is an enlarged view of the stacker with selected panels removed to illustrate the internal components of the assembly. 
     FIG. 3 is an enlarged left side view of the lower half of the stacker in which the lower panel has been removed to expose the turntable assembly. 
     FIG. 4 is a top view of the motor drive assembly for driving the turntable without the rotatable turntable or turntable assembly. 
     FIG. 5 is an elevational view of a stacker discharge guard assembly. 
     FIG. 6 is an elevational view taken generally from the right-hand end of FIG.  5 . 
     FIG. 7 is an elevational view of an alternative stacker discharge guard assembly. 
     FIG. 8 is an elevational view taken generally from the right-hand end of FIG.  7 . 
     FIG. 9 is an overhead plan view of the stacker of FIG.  7 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings wherein the showings are for purposes of illustrating the preferred embodiment of the invention only and not for purposes of limiting same, the FIGURES show a stacking apparatus  10  including an infeed assembly  12  for receiving an input stream of folded overlapping printed products or papers, a stacking section  14  for forming the papers into batches, and a turntable assembly  16  for receiving the batches in a stack or bundle and ejecting the bundles in two opposite directions. The stacker is described herein for use in stacking newspapers or papers, however, it should be understood that the stacker is intended for stacking any substantially flat articles including both printed and unprinted materials. 
     With respect to FIGS. 1 and 2, papers exiting a printing press are fed into the stacker  10  in an infeed direction illustrated by the arrow I between an upper conveyor and lower conveyor of the infeed assembly  12 . The papers are preferably fed with their folded side passing initially into the stacking apparatus and with the folded edges of each of the papers overlapping a previous page. The papers are delivered by conveyors in the infeed assembly  12  to the stacking section  14 . 
     The stacking section  14  includes a plurality of forks  18  which are formed of a pair of claws mounted at fixed distances apart along a pair of closed loop drive chains. These forks  18  each receive and support a batch of papers which drop onto the forks from the infeed assembly  12 . Various mechanical and/or optical sensors may be used in connection with the stacking section  14  to count a number of papers in each batch and to control the movement of the forks  18  to obtain a desired number of papers in each batch. The forks  18  are spring loaded to intercept the continuous stream of papers. The stacking section  14  also includes a guide device  20  which guides the trailing edges of the papers as the papers pass onto the forks  18 . The guide device  20  includes a substantially planar guiding surface  22  and a support member  24 . The support member  24  includes slots  26  receiving locking members  28  which allow the position of the guide device  20  to be adjusted to accommodate papers of different sizes. 
     As the forks  18  move downward and reach a bottom of the closed loop drive chains, the forks rotate causing the batch of papers to be released or dropped into the turntable assembly  16 . The turntable assembly  16  includes guide members  30  for supporting the stack of papers on two opposite sides, and end guide members  32  for supporting the stack on the two opposite sides. The guide members  30 ,  32  taper outward at their top edges to receive the papers. The end guide members  32  pivot open and closed to allow the stacks of papers to be ejected from the turntable assembly when the end guide members are in an open position. 
     As a batch of papers is delivered to the turntable assembly  16  by the stacking section  14 , often the stack will be higher on the one side than the other due to the thickness of the fold or spine of the paper. In order to achieve a bundle having an even height, the turntable assembly  16  is rotated 180° between delivery of successive batches of papers. It is also possible to rotate the turntable assembly 90° between delivery of batches when a stack of square papers is being formed. However, in general, stacked papers are not square, thus a 180° rotation is used. 
     The stacking apparatus  10  of FIGS. 1 and 2 also includes an operator station  70  for operator control of the stacking apparatus, an electrical and power supply panel  72  for controlling the coordination of the various functions of the stacker, and a pneumatic control assembly  74  for controlling the various pneumatic devices of the stacker. These control elements may be of any of those control elements which are known to those in the art. 
     FIG. 3 is a side view of a lower portion of the stacking apparatus  10  with the lower side panel removed to expose a lower portion of the turntable assembly  16  and a drive assembly for rotating the turntable assembly back and forth 180°. The drive assembly includes an air operated cylinder  42  or motor for rotating the turntable and two shocks  44 ,  46  for stopping the turntable rotation. A motor for rotating the turntable is preferably the pneumatic cylinder  42 , however, other types of motors may also be used. The cylinder  42  is pivotally attached on a base plate  48  by a cylinder pivot frame assembly  50 . A piston rod  52  of the cylinder  42  is pivotally attached to a portion of the rotatable turntable  60  by a cylinder stud  54  at a point which is displaced from an axis of rotation X of the turntable  40 . The pneumatic cylinder  42  or motor operates to rotate the turntable  40  back and forth through 180° of rotation. 
     The shocks  44  and  46  halt the motion of the turntable  40  more quickly than the cylinder  42  alone and allow the cylinder to rotate the turntable at a speed which is higher than the speeds currently used in stacking devices without shocks. The shocks  44 ,  46  stop the rotation of the turntable  40  by engaging one of two pads  56  mounted on the turntable frame  60 . The shocks  44 ,  46  are preferably heavy duty shocks. 
     The pneumatic cylinder  42  and pivot frame  50  supporting the cylinder, as well as the shocks  44 ,  46  are best illustrated in the top view of FIG. 4, in which the turntable assembly has been omitted for clarity. The turntable  40 , the cylinder  42 , and the shocks  44 ,  46  are mounted on the base plate  48  along with a pneumatic control valve assembly  58  for controlling the pneumatic cylinder. This base plate  48  is rotatable on the base frame  62  of the stacking apparatus to allow the turntable assembly to be rotated to two different positions or orientations to eject bundles in different directions. The base plate  48  is rotated by removing the four bolts  64  which secure the base plate the base frame  62  and rotating the base plate  48  about a central bearing to a new position where the bolts are then resecured. 
     By allowing the rotation of the entire turntable  40 , motor or cylinder  42 , as well as the shocks  44 ,  46 , the stacker can advantageously eject stacks either in the two opposite directions A and B which are parallel to an infeed direction I of the stacker or may eject stacks in the two opposition directions C and D which are normal to the infeed direction I, or it is contemplated that the stacker could even eject stacks in any of the four directions. During normal operation, however, the bundles are typically ejected in one direction and if a malfunction occurs downstream then the bundles are ejected in another direction until the malfunction is overcome. 
     The description of FIGS. 1-4 represents one commercially available stacker. It will be appreciated, however, that other stackers are constructed and operate in a similar manner. 
     FIG. 5 illustrates a door mechanism or opening guard for a stacker illustrated in a first preferred embodiment as a generally rectangular panel  80  which is adapted to be secured to the frame of the stacker. The panel is dimensioned to substantially cover an opening through which the bundles are ejected from the turntable. This opening is represented by numeral  82  in FIGS. 1 and 3. It will be appreciated that the panel is secured to the frame via any suitable fastener arrangement, such as the elongated fastener rods  84 ,  86 . A hinge  90  is preferably disposed at one end of the panel and interconnects the panel to the threaded rods, i.e., the stacker frame. A series of fasteners  92  are spaced along one edge of the panel to secure the hinge thereto. In those stackers which discharge bundles in two directions, for example 180° apart, one of the openings is typically in operation and only if a malfunction occurs, is the second discharge opening required. Thus, for example, the second opening is only occasionally used and is conventionally left open to the work environment so as not to impede the opening should it become necessary to discharge bundles therethrough. Consequently, this second opening is the type of situation where the above described hinged panel would be ideally used. If additional discharge openings are provided from the stacker, then additional guards are required. 
     It will be appreciated that the hinge is intended to be a one-way hinge. Stated another way, the hinge will pivot outwardly away from the turntable to permit a stacked bundle to exit from the turntable to, for example, a downstream conveyor. It will preclude movement in the opposite direction, i.e., it will prevent entry of materials inwardly toward the turntable. 
     The guard assembly is intended to be part of the original manufacture of a stacker or an aftermarket addition to stackers already in commercial use. Although the dimensions of the frame openings of other stackers may vary, the concept of a panel hingedly secured to the frame to cover the less frequently used discharge openings can be easily accommodated in other stackers without departing from the scope and intent of the present invention. 
     A second preferred embodiment of an opening guard for a stacker is illustrated in FIGS. 7-9. Again, a conventional stacker is illustrated that has a pair of discharge openings permitting the bundles to be ejected from the turntable in directions oriented 180° relative to one another. There is some consideration that a panel as described above in conjunction with the embodiment of FIGS. 5 and 6 could adversely impact on the bundle. That is, the bundle has not yet been tied as it leaves the stacker. Accordingly, the bundle is subject to impact with the panel and, depending upon the force imposed by the hinge, there is the potential that some of the printed product could be dislodged or skewed from the bundle. A non-contact sensor is illustrated in the embodiment of FIGS. 7-9. It establishes a sensor field over the area of each opening, that, if broken, will send a suitable signal to control operation of the stacker. 
     More particularly, a transmitter column  100  is secured to the stacker frame. It employs a sensor or series of individual sensors arrayed, for example, in a vertical array to emit a signal or array of signals to a reflective transfer column  104 . The intensity, spectrum, modulation, sequencing, etc. of the signal can be selected from a number of parameters, as well as the control unit that supports the power, diagnostics, transmitter, transfer, receiver, redundant operations, etc. without departing from the scope and intent of the present invention. The transfer column is preferably a reflective surface such as a stainless steel or mirrored surface that re-directs the sensing field to a second column  106 . Column  106  is essentially identical in structure to column  104 . It, too, redirects the sensing field to a receiving column  108 . Thus, in this preferred arrangement, three sensing fields  110 ,  112 ,  114  are established and are oriented generally 90° to the contiguous field. In this manner, the sensing field between columns  100 ,  104  and columns  106 ,  108  establishes a non-contact stacker discharge guard assembly over the discharge openings. Likewise, if bundles are to be discharged in the region between the columns  104 ,  106 , then a non-contact guard is established along that plane also. Thus, it will be understood that a greater or lesser number of discharge openings is contemplated by either adding to or subtracting the number of columns  104 ,  106  from the assembly. For example, a closed-loop arrangement could be used where the transmitter and the receiver columns abut one another and outline a peripheral, polygon arrangement where the signal is transmitted or forwarded via the reflective columns to a next adjacent column. 
     If a bundle is scheduled for ejection from the bucket region, then breaking the field in the particular discharge opening will not interrupt the operation of the stacker. On the other hand, if one of the other fields is interrupted or broken, then operation of the turntable ejection mechanism may be immediately interrupted. 
     The controller that regulates operation of the stacker can be programmed to immediately cease further operation of the stacker if one or more of the fields is broken. It is also contemplated that if the stacker is undergoing an ejection cycle, then the controller would permit the bundle ejection cycle to be completed before the stacker operation (or at least the turntable operation) is terminated. 
     The invention has been described with respect to the preferred embodiments. Modifications and alterations will become apparent to others upon reading and understanding the specification. These modifications and alterations are also contemplated as being a part of the present invention without being expressly stated herein.