Abstract:
An apparatus for supplying sheets to a printing machine having a sliding work plane moving in outward and return runs, so as to subject one or more sheets thereon to printing, a station, in which the work plane pauses, being provided with a gripper for transferring the sheets from the apparatus to the work plane, with the work plane paused in the station. The apparatus includes a gantry bearing a loading plane positioned by a side of the pause station and made vertically mobile from a first variable-height operating position, and a second fixed operating position flanking the pause station. A receiving station of a stack of sheets is positioned by a side of the gantry opposite the work plane, the height of the head sheet of the stack defining a first operating position. A gripper, borne by the work plane, with the work plane in the operating position grips the head sheet of the stack and transfer it onto the work plane.

Description:
DESCRIPTION OF THE PRIOR ART 
       [0001]    Machines are known for printing combinations of writings and/or logos and/or designs on sheets, in particular panels, comprising (see  FIG. 1 ) a work plane L sliding longitudinally, in outward runs N 1  and return runs N 2 , so as to subject one or more panels, arranged thereon, to the action of printing means; the printing is defined after a predetermined number of the runs. 
         [0002]    The work plane includes an area useful for printing, defined by a longitudinal height (i.e. in the movement direction of the plane) and a transversal height; this useful area receives either a panel or a plurality of panels, longitudinally flanked. 
         [0003]    The following relates to a single panel, though it is understood that depending on a length thereof also two or more panels can be treated. 
         [0004]    The loading and unloading of the panels onto and from the work plane is done in pause stations of the work plane. 
         [0005]    The present invention relates to apparatus for supplying sheets (e.g. panels) to the work plane. 
         [0006]    The known apparatus comprise a loading plane C (see  FIG. 1 ) flanked to the station S in which the work plane L pauses, the height of which is such as to enable gripping means associated to the pause station to grip the panel situated on the loading plane C with the aim of transferring it onto the work plane L. 
         [0007]    In a known solution the panel is located manually by an operator on the loading plane; it is clear that the costs attached to the use of manual labour are considerable, also in view of the fact that productivity and reliability tend to diminish due to tiredness. 
         [0008]    In a further known solution (see  FIG. 1  again) a lift E is used, provided with a table (T) on which the stack(s) P 1  and P 2 -P 4  of panels F are arranged. 
         [0009]    The lift is activated in step-fashion so as to enable the head panel of the stack to be collected from panel-gripping and transfer means M associated to the loading plane C which position the panel on the loading plane. 
         [0010]    There are various drawbacks with the known solution described above. 
         [0011]    The size of the lift E reduces the height of the stack P of panels; further, the work of the operators on the loading plane C is made very problematic as the lift E—stack(s) P combination is arranged on the front part of the loading plane C (see  FIG. 1 ). 
         [0012]    If two or more panels F are supplied onto the loading plane, a same number of stacks P 1 -P 4  has to be loaded, which have to be freed of their protective coverings, flanked correctly and exhibit a same height so as to optimise the functioning of the panel F gripping and transfer means M associated to the work plane. 
         [0013]    It is clear how complex this working system is, and how it involves the use of manual labour. 
       SUMMARY OF THE INVENTION 
       [0014]    The aim of the invention is to provide an apparatus for supplying sheets to the work plane of a printer, which obviates the drawbacks present in the prior art. 
         [0015]    A further aim of the invention is to provide an apparatus that is structurally simple considering the performance it offers, plus the fact that it is extremely functional. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    The above aims are attained in accordance with the contents of the claims. The characteristics of the invention are set out in the following with reference to the accompanying tables of drawings, in which: 
           [0017]      FIG. 1  is a schematic perspective view of an apparatus of known type, mentioned in the preamble hereto, for supplying panels to a printing machine; 
           [0018]      FIG. 2  is a schematic lateral view of the apparatus of the invention; 
           [0019]      FIGS. 3 ,  4  are two perspective views of the apparatus of  FIG. 2  which supplies the above-mentioned printing machine respectively with largest-format panels and smallest-format panels; 
           [0020]      FIG. 5  is a schematic perspective view of a variant of the conveyor used with the apparatus; 
           [0021]      FIG. 6  is a schematic lateral view of the detail I of  FIG. 5 ; 
           [0022]    FIGS.  7 A, 7 B are section views of section VII-VII of  FIG. 5 , relating to the rest configuration and work configuration of a further variant of the conveyor; 
           [0023]      FIGS. 8A ,  8 B are schematic section views of the apparatus of the present invention according to a variant, in different operative configurations; 
           [0024]      FIG. 9  is a schematic lateral view of the apparatus of the invention according to a further variant. 
       
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0025]    With reference to the figures, L denotes the work plane of a known printer  100  denoted in its entirety as of known type; as already mentioned, the work plane L is mobile in the outward N 1  and return N 2  runs, which in  FIG. 2  are both perpendicular to the plane of the sheet. 
         [0026]    The apparatus of the present invention, denoted in its entirety by reference numeral  10 , is arranged by a side of the pause station S of the work plane L. 
         [0027]    The apparatus comprises a gantry  1  which supports, with known means  2 A,  2 B, a work plane  3  constituted by the upper branch  4 A of a closed-loop conveyor  4  borne by the gantry; in the illustrated embodiment, the conveyor is constituted by a series of flanked belts  80 A,  80 B,  80 C,  80 D, winding on a common drive roller  90 A and a common driven roller, not illustrated. 
         [0028]    The loading plane  3  is vertically mobile (directions X 1 , X 2 ), powered by known-type motors (not illustrated). 
         [0029]    The conveyor  4  is motorisable (in a known way, not illustrated) in step-fashion, or continuously, so that the upper branch  4 A translates in direction Y; note that the longitudinal development of the upper branch is at least equal to the longitudinal height of the work plane L, and the width thereof is at least equal to the width of the work plane L. 
         [0030]    A receiving station  70  of a stack  15  of panels  200 ,  300 , arranged on a relative bench  30 A,  30 B, is located flanked to the gantry  1 , on an opposite side with respect to the work plane L. 
         [0031]    The depth B of the stack is not greater than the width of the useful area of the work plane L; the longitudinal dimension of the stack  15  is not greater than the longitudinal height of the useful area. 
         [0032]      FIG. 3  illustrates the maximum format of the panels  200  on which the printing machine  100  can print;  FIG. 4  illustrates a panel format  300  that is smaller than the maximum possible. 
         [0033]    The panel  20  gripping and transfer M means, borne by the loading plane  3 , are denoted in  FIGS. 2-4  generically as they can be made in any way. 
         [0034]    The functioning of the apparatus of the invention will now be described. 
         [0035]    The operator loads at least a stack  15  into the receiving station  70 . 
         [0036]    According to the height H of the stack (indicated with a broken and dotted line in  FIG. 2 ) with respect to the reference line “O” (still with reference to  FIG. 2 ), the loading plane  3  is translated so as to be positioned at the head panel of the stack  15 ; the first operating position K of the loading plane  3  (indicated with a broken line in  FIG. 2 ) corresponding to the height H of the stack. 
         [0037]    The first operating position K is height-variable as it depends on the height of the stack which diminishes with the collection of the head panels from the stack. 
         [0038]    The apparatus  1  comprises detecting means of the height of the head panel of the stack  15  and detecting means of the height of the loading panel  3 : these means have not been denoted since they belong to the prior art. 
         [0039]    At this point the means M are activated, and first grip the head panel of the stack  15  before transferring the panel onto the loading plane  3 , more precisely on the upper branch  4 A of the conveyor  4 . 
         [0040]    In phase relation with the completion of the transfer (disengagement of the means M from the panel), the loading plane  3  is newly moved (directions X 1  or X 2 ) with the aim of positioning the loading plane  3  optimally, and predeterminedly, with respect to the pause station S of the work plane L, the second operating position Q ( FIG. 2 ) being fixed as it is a function of the height of the work panel L. 
         [0041]    This enables the gripping means MP associated to the pause station S of the printing machine to grip the panel located on the upper branch  4 A of the conveyor  4  with the aim of locating it on the work plane L of the printing machine (see a step of this operation indicated with a broken line U in  FIG. 2 ). 
         [0042]    The transfer of the panel from the upper branch  4 A to the work plane L can be optimised according to the variant illustrated in  FIGS. 7A ,  7 B. 
         [0043]    This variant includes a series of shafts  50 , parallel to one another and located at a same height, each being located at the space  60  afforded between the opposite edges of the upper branches of two adjacent belts; each shaft  50  affords a longitudinal flattening  50 A. 
         [0044]    The shafts  50  are motorised in synchrony using known systems, and a positioned so as not to interfere with the relative flattenings  50 A, and with the shafts in the rest position R, against the topmost panel borne by the belts: see  FIG. 7A . 
         [0045]    The synchronous rotation of the shafts  50  in direction P (work position W) causes the raising of the panel (which therefore is disengaged from the belts) and the translation thereof (arrow G) towards the pause station of the printing machine: this facilitates the gripping of the panel by the gripping means MP. 
         [0046]    The motor means vertically moving the loading plane  3  depend on the detecting means of the head panel of the stack and the detecting means of the loading plane; these means act in combination to define the first K and second Q operating positions. 
         [0047]      FIG. 3  illustrates the maximum format of the panels; the head panel  200 A of the stack is transferred onto the upper branch  4 A of the conveyor  4 ; in this case the upper branch is not moved. 
         [0048]      FIG. 4  illustrates a panel, the format of which is smaller than the maximum format. 
         [0049]    The means M position the head panel  300 A of the stack  15  on the initial part of the upper branch  4 A of the conveyor  4  (position Z 1  denoted in a broken line in  FIG. 4 ); in phase relation with this operation, the upper branch  4 A translates in direction Y by an amount greater than the longitudinal dimension (i.e. direction Y) of the panel: the conveyor moves in step-fashion. 
         [0050]    It follows that a series of panels  300  become arranged on the upper branch  4 A (positions Z 1 , Z 2 , Z 3  . . . ) until all the longitudinal extension of the branch  4 A iw covered; this enables transferring the series of panels on the work plane L via the means MP. 
         [0051]    Between a transfer and another of panels from the stack  15  to the upper branch  4 A, the loading plane  3  translates vertically so as to cyclically be arranged in the first H and second Q operating position: this optimizes the transfers. 
         [0052]    A further variant of the conveyor  4  is comprised, which is particularly advantageous, with the conveyor being driven in continuous motion (see  FIGS. 5 ,  6 ). 
         [0053]    With reference  FIGS. 5 and 6 ,  55  denotes abutments positioned transversally to the translation direction Y of the upper branch of the conveyor  4 . 
         [0054]    Each abutment is constituted by a sort of comb, tines  56  of which are arranged at the spaces  60  and exhibit dimensions such as to freely insert in the spaces. 
         [0055]    The downstream abutment  55 A is fixed, while the other abutments are made mobile (in a known way, not illustrated) from a lowered position A 1  (denoted in an unbroken line in  FIG. 6 ) to a raised position A 2  (denoted in a broken line in  FIG. 6 ). 
         [0056]    In the raised position A 2  the tines  56  constitute a same number of abutments for the panels located on the upper branch of the conveyor and arranged correspondingly upstream thereof; in this situation there is a dragging between the panels and the underlying belts. 
         [0057]    In the lowered position A 1  the tines  56  do not interfere with the displacement of the panels in direction Y. 
         [0058]    With maximum-format panels  200  ( FIG. 3 ), the abutments  55  are maintained in the lowered position A 1 ; it follows that each panel transferred onto the conveyor  4  abuts on the fixed abutment  55 A. 
         [0059]    With panels  300  having a smaller format than the maximum, for example as illustrated in  FIG. 4 , the abutments  55  are activated cyclically (lowered position A 1  and raised position A 2 ) in phase relation with the activation of the panel gripping and transfer means M, such as to define, for each panel  300 , the positions Z 1 , Z 2 , Z 3  . . . ) 
         [0060]    In the preferred embodiment of the apparatus one stack alone is used; this enables moving one stack only to the station  70  with all the advantages that this brings. 
         [0061]    No lift is included in the last station, which makes available the space which, in the prior art, is occupied by the lift; further, access to the loading plane  3  is facilitated. 
         [0062]    As the loading plane is vertically mobile, the gripping of the panel at the head of the stack is optimised as well as transfer thereof onto the loading plane and transfer of the panel or panels from the loading plane to the work plane L of the printer. 
         [0063]    In a variant of the invention, illustrated in  FIGS. 8A ,  8 B,  8 C,  9 , the apparatus further comprises conveyor means  16  having a longitudinal development parallel to the longitudinal development of the loading plane  3 , which are arranged on the same plane as the apparatus (in particular, considering a plan view of the apparatus, flanked to the loading plane  3 ), and which extend upstream of the loading plane  3 , to the receiving station  70 . 
         [0064]    In particular, the conveyor means  16  are conformed and dimensioned so as to support a plurality of stacks  15  of sheets flanked to one another (in particular a plurality of sets each formed by a stack  15  and a relative bench  30 A,  30 B flanked to one another), and are activatable (stepped or continuously) so as to transfer each stack  15  of sheets from the loading station  160  to the receiving station  70  (in a first advancement direction V, indicated by the arrow of  FIGS. 8A-8C ,  9 ). 
         [0065]    In other words, with this variant an operator loads, with the aid of known means, each stack  15  of sheets, supported by the relative bench  30 A,  30 B, on the conveyor means  16 , at the loading station  160 . 
         [0066]    Then the activated conveyor means  16  transfer the stacks  15  of sheets one at a time to the receiving station  70  (see  FIG. 8A ), in which the sheets are picked up as described above. During the picking-up of the sheets from a stack  15 , the conveyor means  16  are clearly deactivated (situation of  FIG. 8B ). 
         [0067]    Once all the sheets of a stack  15  have been picked up by the gripping and transfer means M, the conveyor means  16 , newly activated, transfer the empty bench  30 A,  30 B to an unloading station  161 , downstream of the receiving station  70 . At the same time, another stack  15  of sheets is conveyed to the receiving station  70  (see in particular  FIG. 8C ). 
         [0068]    This variant advantageously enables optimising the productivity of the apparatus and all the printing system, reducing the times required for the predisposing of the stacks  15  of sheets to the receiving station  70 , and also for transferring the benches  30 A,  30 B once empty from the receiving station  70 . The apparatus of this variant can further comprise sensor means  18  (illustrated schematically and visible in particular in  FIGS. 8A and 8B ), arranged along the extension of the conveyor means  16 , downstream of the loading station  160  and upstream of the receiving station  70 , so as to detect the conveying of a stack  15  of sheets to the receiving station  70  and for consequently deactivating the movement of the conveyor means  16 . 
         [0069]    In other words, the sensor means  8  detect the transfer of a stack  15  of sheets to the receiving station  70 , and deactivate the movement of the conveyor means  16  so as to enable picking-up of the sheets by the gripping and transfer means M. 
         [0070]    This specification advantageously enables further optimising the functioning of the apparatus according to the invention with respect to the prior art. 
         [0071]    The conveyor means  16  can alternatively be activated and deactivated manually by an operator, who acts for example on a button (this situation is not illustrated). 
         [0072]    In the preferred embodiment illustrated in  FIGS. 8A ,  8 B,  8 C and  9 , the conveyor means  16  comprise a roller conveyor. 
         [0073]    The conveyor means  16  can alternatively comprise two roller conveyors, a first and a second, arranged aligned and adjacent to one another. 
         [0074]    The variant described in the following and illustrated in  FIG. 9  is especially advantageous in a case of stacks of sheets exhibiting different parameters to one another, such as for example stacks of sheets  15 ,  15 ′ of different materials. 
         [0075]    In this variant of the invention, the apparatus further comprises a waiting station  162 , arranged downstream of the receiving station  70  (and upstream of the loading station  161 ). 
         [0076]    Further, the conveyor means  16  extend from the loading station  160  to the waiting station  162  (therefore beyond the receiving station  70 ) so as to convey, towards the waiting station  162  (following activation thereof in the first advancement direction V), a stack  15 ′ of sheets which has reached the receiving station  70  and which must remain in waiting mode before the relative sheets can be gripped by the gripping and transfer means M and transferred to the printing machine  100  (for example a stack  15 ′ of sheets of a determined material which is to be processed subsequently, as will become clearer in the following). 
         [0077]    In particular, the conveyor means  16  are further activatable in a second advancement direction V′, opposite the first advancement direction V (along the same direction) so as to be able to newly transfer the stack of sheets  15 ′ from the waiting station  162  to the receiving station  70 . 
         [0078]    According to this variant, the apparatus can further comprise reading means  19 , arranged along the extension of the conveyor means  16  (between the loading station  160  and the receiving station  70 ), so as to verify whether each stack of sheets  15 ,  15 ′ is to be conveyed towards the waiting station  162 , as will become clearer in the following. 
         [0079]    It can occur that two or more stacks  15 ,  15 ′ of sheets, each constituted by sheets of different materials, are loaded at a same time on conveyor means  16 , so as to be transferred towards the receiving station  70  and therefore be subjected to the printing processes. However, the order in which the stacks  15 ,  15 ′ are loaded onto the conveyor means  16  might not coincide with the order in which the stacks  15 ,  15 ′ have effectively to be processed by the printing machine  100 . Usually, certain printing jobs are performed on sheets of a same material, so that it is necessary to process (or transfer towards a same printing machine  100 ) the sheets of the same material until the printing job has been completed. 
         [0080]    Thus, in a case in which sheets of a first material are in the printing step and a stack  15 ′ of sheets of a second material is being conveyed to the receiving station  70 , this stack  15 ′ is temporarily transferred (activating the conveyor means  16  in the first advancement direction V) to the waiting station  162 , until the processing of the sheets of the first material has concluded. At this point, the conveyor means  16  are activated in the second advancement direction V′ so as to process the stack  15 ′ of sheets of the second material. 
         [0081]    A bar code, for example, can be included on each bench  30 A,  30 B supporting a stack  15 ,  15 ′; the bar code identifies the type of material of the sheets of the stack  15 ,  15 ′ supported by the bench  30 A,  30 B. In this case, the reading means  19  can comprise for example a bar-code reader for conveying, if necessary, the stack  15 ,  15 ′ towards the waiting station (i.e. in a case where from a reading of the bar codes it is established that the sheets of the stack  15 ′ are constituted by a different material from the material of the sheets under process). 
         [0082]      FIG. 9  clearly shows the above-described variant, and in particular a stack of sheets  15  of a first type of material is illustrated, the sheets of which are about to be picked up by the gripping and transfer means M, and a further stack of sheets  15 ′ of a second type of material in waiting mode in the waiting station  162 . 
         [0083]    This variant is advantageously especially flexible in a case of stacks of sheets  15 ,  15 ′ of different materials, as it avoids having to halt the printing process and optimises the total working times. 
         [0084]    The above has been described by way of non-limiting example, and any variants, for example in the station  70  two or more stacks can be stationed, are understood to fall within the protective scope of the present invention as described above and as claimed in the following.