Abstract:
An apparatus for trimming a plurality of printed products includes at least one trimming station including a yoke, at least one blade positioned on the yoke and a trimming transport device arranged to transport the plurality of printed products inside the at least one trimming station. A feeding conveyor is arranged to feed the printed products to the trimming station. At least one driver is coupled to and operative to drive the yoke, the feeding conveyor, and the trimming transport device, respectively. A control unit is coupled to the at least driver and operative to control the adjustment of the phase position of the feeding conveyor relative to the yoke.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a divisional of U.S. patent application Ser. No. 11/714134 filed Mar. 6, 2007, now U.S. Pat. No. ______, which claims the priority of European Patent Application No. 06405104.8-2302, filed on Mar. 9, 2006. The subject matter of the foregoing applications is incorporated herein by reference in their entireties. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of Invention 
         [0003]    The invention relates generally to printing products and more particularly to a method and apparatus for automatic trimming of printed products, such as brochures, magazines, catalogues, and book blocks. 
         [0004]    2. Description of the Related Art 
         [0005]    Conventional apparatuses for automatic trimming of printed products, such as brochures, magazines, catalogues, and book blocks, are provided with a trimming station including one or more blades positioned on a vertically moving yoke. The printed products are supplied successively from a feeding conveyor to the trimming station, where the printed products are trimmed on the edges by one or more blades. 
         [0006]    One such conventional trimming apparatus, disclosed in document European Patent document EP 1 166 977 A1, is a so-called three-side trimmer, in which one blade of the trimming station trims the front edge of one printed product while two other blades simultaneously cut the top and bottom of another printed product. The printed products are supplied to the trimming station from a conveying belt that includes a number of dividers, against which the printed products are lined up. At the end of the conveying belt, the printed products are clamped and held in place between an upper and a lower belt before being supplied to a trimming transport device in the trimming station. In the trimming transport device, once the printed product has reached the predetermined position, the front edge of the product is trimmed by the first blade. The printed product is then transported further within the trimming transport device, where the top and bottom edges of the printed products are trimmed by the other two blades. In order to trim the desired position of the printed products, a mechanical stoppage device may be provided within the trimming transport device. However, in order to trim the desired position of the printed products more accurately, the trimming station may be provided with a measuring unit that controls the stoppage of the printed material before the trimming takes place. Using the measuring unit, it is possible to dispense with a mechanical stoppage device and hold the printed products in place between an upper belt and a lower belt within the trimming transport device for trimming. With a mechanical stoppage device, however, the printed products would have to be released before the desired stoppage point is reached. 
         [0007]    It is often desirable to trim printed products with varying widths. For example, printed products intended for shipping, in particular by postal mail, may be produced with varying widths. This can be the result of the so-called “selective binding” on a gathering and wire-stitching apparatus. With digital printing presses, these products can be produced successively and such that the format differs from one printed product to another. 
         [0008]    The conventional trimming apparatus discussed above can be used to trim printed products having different widths. To do so, however, a coupling of the drive must be disengaged, the apparatus shut down, and the operation interrupted. Therefore, changing the format of one or more printed products is not practical and cost-effective. Accordingly, it is advantageous to provide a trimming apparatus and a trimming method, which permit the trimming of successive printed products having varying widths at full operational speed without reducing output. 
       SUMMARY OF THE INVENTION 
       [0009]    It is an object of the present invention to provide an apparatus and method for trimming printed products that would permit the trimming of successive printed products having varying widths at full operational speed without reducing output. 
         [0010]    This and other objects are achieved by the invention, wherein, according to one embodiment, there is provided an apparatus for trimming the printed products, comprising: at least one trimming station including a yoke, at least one blade positioned on the yoke and a trimming transport device arranged to transport the plurality of printed products inside the at least one trimming station; a feeding conveyor arranged to feed the printed products to the trimming station; at least one driver coupled to and operative to drive the yoke, the feeding conveyor, and the trimming transport device, respectively; and a control unit coupled to the at least driver and operative to control the adjustment of the phase position of the feeding conveyor relative to the yoke. 
         [0011]    According to an embodiment of the invention, the phase position of the feeding conveyor relative to the moveable yoke may be changed for any two successive printed products that have different format widths. According to a yet further embodiment of the invention, changing the phase position may depend on the format width of the printed product being fed from the feeding conveyor to the trimming station. According to the aforementioned embodiments of the invention, the phase position of the feeding conveyor relative to a yoke drive is adjusted to adapt the respective format width of the printed product that extends in conveying direction. This adaptation is realized by controlling the movement of the feeding conveyor and the yoke. 
         [0012]    In some embodiments, each printed product may be lined up in the conveying direction against a divider. In particular, the individual printed products may respectively come to rest with the bound edge pushed against a divider and the edge to the trimmer trailing. In some embodiments, the dividers may further be positioned with approximately uniform spacing on the feeding conveyor. 
         [0013]    In some embodiments, the printed products may be guided within the trimming transport device on a circulating belt. According to another embodiment, the printed products may be held while clamped between an upper and a lower belt, so as to permit a precise guidance and a high trimming quality. In further embodiments, trimming transport device and the feeding conveyor may each include circulating upper and lower belts for guiding the printer products. 
         [0014]    In some further embodiments of the invention, the position of each of the printed products in the trimming transport device may be measured, and if the position of the printed product differs from a desired predetermined position, the position of the printed product in the trimmer transport device may be corrected. Accordingly, the printed products may be trimmed with high precision. In other embodiments of the invention, however, an adjustment of the printed product to the desired position is possible even without the measuring unit. In such embodiments, the printed products can be held in place clamped-in between upper and lower belt and can be guided precisely to a desired position during the trimming operation. Therefore, the adjustment of the desired position and a virtual end stop as disclosed in EP 1 166 977 A1 is still possible. 
         [0015]    According to a further embodiment, the trimming transport device and the yoke are advantageously driven by two separate motors, such as servomotors, which would permit an extremely quick change/conversion for successive printed products with different formats. The conversion may occur automatically during the operation, meaning the apparatus need not be shut down for a format change. Accordingly, it is possible to trim successively printed products having different formats, resulting from the so-called “selective binding.” 
         [0016]    In embodiments of the invention, the printed products may be respectively secured in the feeding conveyor until they are fully transported from the feeding conveyor to the trimming transport device. In such embodiments, the phase change begins as soon as the printed products are fully transported from the feeding conveyor and no printed products are located in the transfer region between the feeding conveyor and trimming transport device. In these embodiments, there is sufficient time for adjusting the phase position of the feeding conveyor relative to the yoke while trimming of the printed product currently positioned on the trimming transport device. Accordingly, it is possible to feed successive printed products having different format widths, e.g. in the range of 10-20 mm. 
         [0017]    In embodiments of the invention, it is possible to change from a comparatively large product width to a considerably smaller product width for the following printed product and then again back to the comparatively large product width, without having to interrupt the transport. 
         [0018]    In some embodiments, the printed products may be transferred from the feeding conveyor to the trimming transport device and guided by both conveyors during this transfer, wherein the two conveying devices are driven with synchronized speed at the time of transfer. The drivers for the feeding conveyor and preferably also the trimming transport device may be dynamic drives with corresponding motors, for example synchronous motors with rotational angle control. 
         [0019]    In one embodiment of the invention, the trimming apparatus is embodied as a so-called three-knife trimmer. Other embodiments, however, may be implemented in which the trimming apparatus executes only one cut, for example a frontal cut, or two cuts, or even more than three cuts. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    These and other features and advantages of the invention will be further understood from the following detailed description with reference to the accompanying drawings, which are depicted as follows: 
           [0021]      FIG. 1  is a schematic side view of a trimming apparatus according an embodiment to the invention; 
           [0022]      FIG. 2  illustrates the movement graphs for two different formats, wherein the horizontal axis indicates the position of the yoke and the vertical axis indicates the position of the feeding conveyor; and 
           [0023]      FIG. 3  illustrates a different movement curve, wherein the horizontal axis again indicates the position of the yoke and the vertical axis indicates the position of the trimming transport device. 
       
    
    
     DETAILED DESCRIPTION 
       [0024]    The trimming apparatus shown in  FIG. 1  is provided with a trimming station  5  to which printed products  3  are supplied successively from a feeding conveyor  2 . These printed products  3  are conveyed on the feeding conveyor  2  in the direction of arrow  4  after arriving, for example, from a gathering and wire-stitching apparatus that is not shown herein. The printed products  3  may include brochures, magazines, catalogues, book blocks and the like. The printed products  3  have a bound leading edge  26  that extends in the conveying direction, as shown with arrow  4 . The printed products  3  may, for example, be stitched along this bound edge  26 . The printed products  3  may be conveyed on the conveyer belt  16  at a distance to each other, each being lined up against a divider  6 . 
         [0025]    The printed products  3  are transferred successively via a trimming transport device  10  within the trimming station  5 . In this trimming station  5 , the printed products  3  are trimmed on the front with a blade  12  and on the top and bottom with two blades  13  (only one blade shown). The trimming transport device  10  is used for positioning the printed products  3  to be trimmed and for transporting the products from a first location a′ where the front is trimmed to a second location a″ where the top and bottom are trimmed.  FIG. 1  shows a printed product  3 ′ in position a′ for the frontal trimming and a printed product  3 ″, whose front edge has already been trimmed, in position a″ for the top and bottom trimming. The printed products  3 ,  3 ′, and  3 ″ can have different formats and different product widths. The formats and/or product widths and/or data relating thereto, which may be stored, for example, in a printing press that is not shown herein and/or a gathering and wire-stitching apparatus not shown herein, are available for the control of the trimming apparatus. 
         [0026]    A driver  1  is used to drive and operate the feeding conveyor  2 . The driver  1  is attached to a drive roller  29  around which a traction device is fitted, for example a chain or toothed belt. During the operation of the feeding conveyor belt  16 , the dividers  6  are moved in the direction of arrow  4  towards the trimming station  5 . In the region of the drive roller  29 , the dividers  6  move around the drive roller  29  and thus away from the printed product  3 , in a downward direction. At about the same time, the printed products  3  are each gripped by an upper belt  8  and a lower belt  77  and are conveyed further at the same speed and in the same direction of arrow  4 . The printed products  3  are held in place and guided by the upper belt  8  and the lower belt  7 , which are also operated by the driver  1 . The driver  1  is a dynamic driver, which allows changing the speed of the feeding conveyor belt  16 , as well as the speed of upper belt  8  and lower belt  7 , at any time and on short notice. The lower belt  7  and the upper belt  8  may respectively consist of several partial belts, arranged side-by-side and at a distance to each other, so that the dividers  6  can move between these partial belts. The feeding conveyor belt  16  can also consists of several partial chains. 
         [0027]    The trimming transport device  10  is provided with a separate, also dynamic driver  9  that comprises a motor as well as a control unit  40  in the form of a position transmitter. The conveyor is driven by a drive roller  28 , arranged at a distance to a deflection roller  19 . For the frontal trimming, the printed products  3  are positioned between a lower belt  41  and an upper belt  42  and are subsequently conveyed further down the trimming transport device for the top and bottom trimming. In  FIG. 1 , the printed product  3 ′ is in position to be trimmed on its front edge by blade  12 . The blade  12  is attached to a yoke  11 . The front of printed product  3 ″ has already been trimmed on the front edge  27  and the product in now in position for the top and bottom trimming. As seen in the conveying direction  4 , the bound edge  26  is leading and the front edge  27  is trailing. The printed product  3 ″ is positioned underneath the two blades  13 , of which only the front blade is visible in  FIG. 1 . The two blades  13  are also attached to yoke  11 , which is positioned on a machine frame that is not shown herein and can move vertically up and down with limitations, as shown with double arrow  14 . The yoke  11  is moved with the aid of a third driver  39 , which can be embodied as dynamic drive. The third driver  39  is connected to control unit  40 , which in turn is connected to the driver  1  and the driver  9 . 
         [0028]    A measuring unit  15  for sensing the respective position of a printed product  3  is arranged near the trimming transport device, past the blade  12  in the conveying direction  4 . The measuring unit  15  may include, for example, an optical sensor, and is not shown in further detail herein. The measuring unit  15  records the position of the front edge  27  and/or the bound edge  26  of an incoming printed product  3  and transmits this position to the control unit  40 . Deviations from the desired position can subsequently be corrected by adjusting the trimming transport device  10 , which is driven by the dynamic driver  9 , which itself is controlled by the control unit  40 . Accordingly, it is possible to precisely adjust the desired position shown in  FIG. 1 , even without a mechanical stoppage device. For further disclosure, please refer to the previously mentioned EP 1 166 977 A, the content of which is incorporated in its entirety herein by reference. The measuring unit  15  is not necessary, but does permits a higher trimming precision. 
         [0029]    The feeding conveyor  2  transfers the individual printed products  3  to the trimming transport device  10 . The printed products  3  leave the feeding conveyor  2  at the location of two deflection rollers  17  and  18 , arranged one above the other, and are then gripped respectively at the bound edge  26  in the region of a deflection roller  19  with a corresponding upper deflection roller. During the feeding of the printed products  3  into the trimming station, the printed products are jointly gripped and guided during a specific interval by both the feeding conveyor  2  and the trimming transport device  10 , during which the feeding device  2  and the trimming transport device  10  operate at a synchronized speed. Once the respective printed product  3  leaves the feeding conveyor  2 , the speeds for the feeding conveyor  2  and the trimming transport device  10  can be controlled independently. Such control is possible in the arrangement depicted in  FIG. 1 , in which the printed product  3 ′ has left the feeding conveyor  2  and is guided solely by the trimming transport device  10 . The following printed product  3  is positioned completely in the region of the feeding conveyor  2 . In this arrangement, the phase position of the printed product  3  relative to the yoke  11  can be changed, so as to achieve an adaptation to the format width of a printed product  3 . As used herein, adjusting or changing the phase position of the feeding conveyor relative to the yoke, means that a point in the cyclical cutting operation of the yoke, for example lower dead center, is adjusted relative to the cyclical operation of the feed conveyor or vice versa, in order to adjust the sequence of movement of the cutting blades in the trimming operation. This may be achieved, for example, by adjusting the frequency of the cyclical operation of the yoke, or adjusting the cyclical speed of the feed conveyor, or both. The adjustment of the phase position is necessary when there is a change in format width so that the printed product with the new format width will be trimmed at the proper location. This operation is explained in further detail in the following with reference to  FIGS. 2 and 3 . 
         [0030]    In the representation according to  FIG. 2 , the horizontal axis  30  corresponds to the position of the yoke drive  39 . At points  31 , the yoke  11  is always positioned in the lower dead center, in which the individual printed product  3  has already been trimmed and the knives  12  and  13  are again moved upward. The vertical axis  32  corresponds to the position of the drive  1  and thus the feed-in position. At points  33 , the bound edge  26  of the printed product  3  is positioned at the start of the trimming transport device  10 . Lines  34  indicate where the printed product  3  has been fully transported from the lower belt  7 , the upper belt  8  of the feeding conveyor  2 . The straight line  35  represents the transport of a printed product  3 , having a large product or format width, whereas the line  36  represents the transport of a printed product  3  with a smaller product and format width. 
         [0031]    The more emphasized line  37  represents the area of format change during a change-over from a printed product with large format width (line  35  of  FIG. 2 ) to a printed product with small format width (line  36  of  FIG. 2 ) and back again to a printed product with a large format width (line  35  of  FIG. 2 ). In the two regions  38 , no printed product  3  is located in the area of transfer from the feeding conveyor  2  to the trimming transport device  10 . As can be seen, since the format widths of the successive printed products  3  are different, the phase position of the feeding conveyor  2  relative to the yoke  11  is changed in these regions  38 . Between the two regions  38 , however, a printed product  3  is gripped jointly by the feeding conveyor  2  and the trimming transport device  10 . The two conveying devices move at the same speed in this area and, accordingly, there is no change in the phase position relative to the drive  39 . A comparatively small time window is available for the adaptation to the format width. However, this time window is sufficient for effecting a format change of 20 mm, for example, while the production speed remains unchanged. 
         [0032]    In the representation according to  FIG. 3 , the horizontal axis  20  indicates the position of drive  39  on the yoke  11 . Points  21  respectively indicate the position of the yoke  11  in the lower dead center. The vertical axis  22  corresponds to the position of the trimming transport device  10  and/or the drive  9 . At points  23 , a printed product  3 ′ is in the idle position, meaning the correct position for trimming. The printed product  3 ′ is trimmed in an area  24 , shown herein with hatching. Line  25  marks the transition from a region in which a printed product  3  is gripped by the feeding conveyor  2  as well as the trimming transport device  10 . The position of line  25  and/or the limiting area depends on the format width of the respective printed product  3 . In this region, the feeding conveyor  2  operates at the same speed as the trimming transport device  10 . Downstream of the line  25  shown in  FIG. 3 , the aforementioned printed product  3  has left the lower belt  7  and the upper belt  8 . The phase position relative to the yoke  11  can thus be changed until the printed product  3  reaches the rest position and thus the desired position for trimming. 
         [0033]    The invention consequently allows producing postal shipments that meet route requirements, i.e. the printed products are produced and packaged in the manner in which they are distributed later on by the postal service. Printed products with different formats, intended for the same addressee, can be produced successively on the same apparatus. 
         [0034]    The invention has been described in detail with respect to various embodiments, and it will now be apparent from the foregoing to those skilled in the art, that changes and modifications may be made without departing from the invention in its broader aspects, and the invention, therefore, as defined in the appended claims, is intended to cover all such changes and modifications that fall within the true spirit of the invention.