Patent Publication Number: US-6216594-B1

Title: Plate replacing system

Description:
FIELD OF THE INVENTION 
     The present invention relates to a plate replacing system of a rotary press, especially a web rotary press. 
     BACKGROUND OF THE INVENTION 
     Regarding a web rotary press having a plurality of printing units arranged ina row, various proposals have been made for a device which automatically attaches a predetermined printing plate, distributed to each fixed position of the plurality of printing units, to a predetermined position of each plate cylinder of the printing unit, and which automatically detaches the printing plate from the plate cylinder. 
     For example, Japanese Unexamined Patent Publication No. 74654/87 discloses a device using a robot provided with a hand having a sucking disk capable of holding a printing plate. Japanese Patent Publication No. 67023/91 shows a device comprising four interrelated base plates, coarse adjustment means provided on the first and second base plates so as to be capable of contacting and separating a printing plate with and from a predetermined position of a plate cylinder, printing plate fine adjustment means provided on the third and fourth base plates so as to be capable of properly placing a printing plate leading edge bend on a plate cylinder edge, printing plate holding means provided on the fourth base plate, means provided on the fourth base plate for bending a printing plate body along a circumferential surface of the plate cylinder, and means provided on the fourth base plate for pressing a trailing edge bend of the printing plate. Japanese Unexamined Patent Publication No. 176149/91 by the present applicant proposes a sheet-feed printing press in which a loader (cassette) capable of holding new and old printing plates is pivotably supported between printing units. 
     The former two devices require meticulous actions, and need a predetermined mechanism for each action. Thus, their structures have to be complicated, thereby inducing cost increases, and making the devices unreliable. The latter device, on the other hand, has a mechanism linked to a plate winding mechanism of a plate cylinder, and needs a predetermined mechanism for each action, as do the former two devices. This device also makes the structure of the loader complicated, thus involving an increased cost and prolonged actions. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide an inexpensive plate replacing system having a simplified structure and capable of smoothly mounting a printing plate on a plate cylinder to shorten the plate replacing time. 
     To attain the above object, the present invention provides a plate replacing system comprising a cassette capable of accommodating a printing plate and supported so as to be pivotable, the cassette being contactable with and separable from a plate cylinder, and a printing plate moving mechanism provided in the cassette for holding the printing plate and moving the printing plate such that a bent front end surface formed at a leading edge front end portion of the printing plate becomes nearly parallel to a gripping support side surface of a plate cylinder gap. 
     The printing plate moving mechanism may deform the printing plate. 
     The printing plate moving mechanism may comprise a holding member for holding the printing plate, a link mechanism for supporting the holding member, and an actuator for driving the holding member via the link mechanism. 
     A pivot fulcrum of the cassette may be placed on a line perpendicular to a line of extension of the gripping support side surface of the plate cylinder gap during mounting of the printing plate. 
     The cassette may be supported on a loader, and the loader may be provided so as to be movable in a cylinder shaft direction, and can be brought into await state toward an operating side of a printing press. 
     The cassette may be supported on the loader so as to be movable in a direction perpendicular to the cylinder shaft direction. 
     The cassette may include an old plate holding unit for holding the printing plate to be removed from the plate cylinder. 
     The old plate holding unit may have an actuator which engages a trailing edge of the printing plate to retract the printing plate into the cassette. 
     The cassette may also include a positioning member which contacts the plate cylinder to position the cassette relative to the plate cylinder. 
     The plate replacing system may further comprise a cassette pivotally driving unit for pivotally driving the cassette to a contacting position at which the cassette contacts the plate cylinder, a separating position at which the cassette separates from the plate cylinder, and an intermediate position located between the contacting position and the separating position. 
     According to the foregoing constitutions, actions for mounting and dismounting the printing plate are performed by the pivoting action of the cassette. Furthermore, mounting of the printing plate on the plate cylinder is carried out smoothly without the need to upsize the cassette, so that the duration of plate replacement can be shortened. Besides, the plate replacing system can be simplified because the driving device can be shared. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein: 
     FIG. 1 is a front view of a plate replacing system showing an embodiment of the present invention; 
     FIG. 2 is a side view of the plate replacing system; 
     FIG. 3 is a structural explanation drawing of the interior of a cassette of the plate replacing system; and 
     FIGS.  4 ( a ) to  4 ( c ) are explanation drawings of an operating state of the plate replacing system., 
    
    
     PREFERRED EMBODIMENTS OF THE INVENTION 
     A plate replacing system according to the present invention will now be described in detail by way of the following Example with reference to the accompanying drawings. 
     EXAMPLE 
     FIG. 1 is a front view of a plate replacing system showing an embodiment of the present invention. FIG. 2 is a side view of the plate replacing system. FIG. 3 is a structural explanation drawing of the interior of a cassette of the plate replacing system. FIGS.  4 ( a ) to  4 ( c ) are explanation drawings of an operating state of the plate replacing system. 
     As shown in FIGS. 1 and 2, ink rollers  2 , a plate cylinder  3 , and a blanket cylinder  4  are rotatably supported between right and left frames  1  of a web rotary press so that a web passing between the blanket cylinder  4  and a blanket cylinder (not shown) is printed. Needless to say, this set of cylinders arranged constitutes one printing unit, and a plurality of the printing units are arranged in a row in the direction of travel of the web, although this is not shown. 
     Between the upper surfaces of the right and left frames  1  corresponding to each printing unit, a channel bar  7  is provided to span the gap between these upper surfaces. One end of the channel bar  7  is projected over a predetermined length toward an operating side of the printing press (such that the length of the channel bar  7  exceeds the length between the right and left frames  1 ). On a side surface of, and over the entire length of, the channel bar  7 , a rail  8  of a linear guide is laid. Above the rail  8 , a rack  9  is fixedly provided parallel to the rail  8 . 
     On the rail  8 , a loader  10  for plate replacement for the plate cylinder  3  is held downwardly via a plurality of (three in the drawing) bearings  11  of the linear guide so as to be movable in a cylinder shaft direction. That is, the loader  10  runs below the rail  8 . 
     The loader  10  suspends fixed frames  13  in a gate-like form from both ends of a stay  12  fixed to the bearings  11 . On these fixed frames  13 , moving frames  15  are turnably (pivotably) supported via pins (fulcrums)  14 . Between these moving frames  15 , a cassette  16  capable of accommodating new and old printing plates W 1  and W 2  is supported so as to be movable in a vertical direction (a longitudinal direction of the moving frame  15 ). Alternatively, a pin receiving member (hole) may be provided in the fixed frame  13 , while a pin may be supported on the moving frame  15 , so that the moving frame  15  can turn relative to the fixed frame  13 . 
     In detail, a first air cylinder  17  for a long stroke and a second air cylinder  18  for a short stroke, whose suction heads are rigidly bonded to each other, are interposed between the fixed frame  13  and the moving frame  15  on each of the right and left frames  1 . A front end of a piston rod of the first air cylinder  17  is pinned to a lower end portion of the moving frame  15 , while a front end of a piston rod of the second air cylinder  18  is pinned to a lower end portion of the fixed frame  13 . 
     When the first air cylinder  17  expands, the front end of the cassette  16  turns from a position a (starting point) to a position b (intermediate point) in FIG.  2 . Based on this position b, the second air cylinder  18  expands and contracts, whereupon the front end of the cassette  16  turns in a reciprocating manner between the position b and a position c (end point) in FIG.  2 . 
     At upper ends of the right and left moving frames  15 , third air cylinders  21  for a short stroke are attached downwardly via brackets  20 . A front end of a piston rod of the third air cylinder  21  is connected to an upper part of a side surface of the cassette  16 . In the drawing, the reference numeral  22  denotes a linear guide interposed between the moving frame  15  and the cassette  16  for guiding the ascent and descent of the cassette  16 . 
     When the front end of the cassette  16  turns between the position a and the position b in FIG. 2, the third air cylinder  21  is contracted to lift (retract) the cassette  16  slightly relative to the moving frame  15  (see a two-dot chain line in FIG.  2 ). As a result, the front end of the cassette  16  is prevented from interfering with a blanket cleaning device  23 , etc. fixedly mounted on the frame  1 . 
     On one of the fixed frames  13 , a motor  26  for loader driving is mounted upwardly at an external upper position. A pinion  27  secured to an output shaft of the motor  26  is engaged with the rack  9 . 
     The cassette  16  comprises a base plate  16   a , and side walls  16   b  erected on the right and left sides of the base plate  16   a . Inside the cassette  16 , a moving mechanism for a new plate W 1  and holding unit for an old plate W 2  are provided which work in association with a publicly known plate winding mechanism (not shown; see Japanese Unexamined Patent Publication No. 66598/97) provided in the plate cylinder  3 . 
     As the moving mechanism for the new plate W 1 , a plurality of suction pads  30  (constituting a holding member, FIG.  3 ,) connected to a vacuum source (not shown) are provided in a front part of the interior of the cassette  16 . The suction pads  30  are fixedly provided in a transverse row on a bar  31  (constituting the holding member) extending in a width direction of the cassette  16  to attract by suction and hold a leading edge of the new plate W 1 . Reference holes  37  (see FIG. 1) formed at the leading edge of the new plate W 1  are the same as those widely used as positioning holes in plate making. A trailing edge of the new plate W 1  is suitably supported by stiffening plates  38  (see FIG. 1) provided on the side walls  16   b  of the cassette  16 . 
     L-shaped brackets  32  are provided on lower surfaces of both ends of the bar  31 . One end of each of two long and short links  33   a  and  33   b  is turnably supported on the side wall  16   b . The other ends of the links  33   a  and  33   b  are turnably connected to and supported by the L-shaped bracket  32  so as to be adjacent to each other. To the point of connection of the L-shaped bracket  32  to the short link  33   b , a front end of a piston rod of an air cylinder (as an actuator)  34  is connected, the air cylinder  34  being attached forwardly to an inner surface of each of the right and left side walls  16   b  of the cassette  16 . 
     Upon expansion and contraction of the two air cylinders  34 , the holding member including the suction pad  30 , etc. reciprocates between a waiting position and an inserting position. Also, by setting the lengths of the long and short links  33   a  and  33   b  as well as the stroke amount of the air cylinder  34 , the new plate W 1  can be deformed such that a leading edge bend  35  of the new plate W 1  (a front end portion of the plate at an acute bending angle) and a gripping support side surface  36   a  of a gap  36  of the plate cylinder  3 , into which a winding rod or the like (not shown) is to be inserted at the time of mounting the printing plate, become nearly parallel to each other during the movement from the waiting position to the inserting position. 
     The fulcrum  14  of the cassette  16  is placed on a line perpendicular to a line of extension of the gripping support side surface  36   a  of the gap  36  in a state in which rotation of the plate cylinder  3  remains stationary at a mounting position of the new plate W 1 . 
     As the holding unit for the old plate W 2 , a guide plate  41  with a -shaped cross section having a front end portion widened like a trumpet is provided inside the cassette  16  so as to be capable of accommodating the entire old plate W 2 . This guide plate  41  may be provided such that there is one guide plate  41  near the inner surface of each of the right and left side walls  16   b  of the cassette  16 . Alternatively, the guide plate  41  may be provided in the form of a single plate continuously extending in the width direction of the cassette  16 . 
     According to the present embodiment, an upper front end portion of the guide plate  41  (facing the suction pad  30 ) assumes a divided form as a moving guide  41   a . To the moving guide  41   a , front ends of piston rods of two air cylinders  43  attached forwardly to the inner surfaces of the right and left side walls  16   b  of the cassette  16  are turnably connected via support brackets  42 . Upon expansion and contraction of the two air cylinders  43 , the moving guide  41   a  is adapted to reciprocate between a waiting position and a guiding position. 
     To front ends of piston rods of two air cylinders  44  attached rearwardly to the inner surfaces of the right and left side walls  16   b  of the cassette  16 , gripper members  45  are fixed. In withdrawing the old plate W 2  while gripping it, the two air cylinders  44  expand, whereupon the gripper members  45  hold a trailing edge of the old plate W 2  to impart tension to the old plate W 2 . 
     In FIGS.  3  and  4 ( a ) to  4 ( c ), the reference numeral  39  denotes a roller provided at the front end of the cassette  16  so as to serve as a positioning member for the cassette. The reference numeral  40  denotes a guide roller provided on one side of the bar  31 . 
     According to the foregoing constitution, the loader  10  is placed at a waiting position (outside the printing press) on a printing press operating side during ordinary printing (when the plate is not replaced). At this waiting position, the new plate W 1  is set in the cassette  16  by an operator&#39;s manual work. At this time, the new plate W 1  is held by the stiffening plates  38  and the suction pads  30  without being deformed, and thus can be set easily. 
     During replacement of the plate for switching of a printing product, operation of the printing press is stopped, and the motor  26  is started at the touch of a button by the operator, or by sequential control by a loader controller. As a result, the loader  10  runs along the rail  8  of the linear guide by the action of the rack  9  and the pinion  27 , and is moved to a plate replacing position opposed to the plate cylinder  3  inside the printing press. 
     When the loader  10  reaches the plate replacing position and the motor  26  is stopped, the first air cylinder  17  of the loader  10  expands to turn the front end of the cassette  16  from the position a to the position b in FIG.  2 . At this time, the third air cylinder  21  has been contracted, so that the cassette  16  has been slightly retracted relative to the moving frame  15 . Thus, when the cassette  16  arrives at the position b, the third air cylinder  21  expands to push out the cassette  16  relative to the moving frame  15 . Then, the second air cylinder  18  expands to turn the cassette  16  to the position c, thereby bringing the roller  39  into contact with the circumferential surface of the plate cylinder  3 . At this position c, an automatic dismounting action for the old plate W 2  is started. 
     At the position c, the winding rod (not shown) of the plate cylinder  3  is loosened by operation of a lever (not shown) present in an end face part of the plate cylinder  3 . On this occasion, the trailing edge of the plate is released from the circumferential surface of the plate cylinder under the plate&#39;s own elastic force, as shown in FIGS.  4 ( a ) to  4 ( c ). Then, when the plate cylinder  3  is rotated counterclockwise, the old plate W 2  is sequentially peeled from the circumferential surface of the plate cylinder, beginning at its trailing edge. While being peeled, the old plate W 2  enters the guide plate  41  of the cassette  16 , and is eventually accommodated therein. At this time, the moving guide  41   a  lies at a guiding position indicated by a two-dot chain line in FIG.  4 ( a ) because of the contraction of the air cylinder  43 . 
     Meanwhile, the time comes when only a bend of a leading edge of the old plate W 2  is left in the plate cylinder  3 . At this time, the air cylinder  44  expands, whereupon the gripper member  45  holds the trailing edge of the old plate W 2  to impart tension to the old plate W 2 . After this tension impartment, the second air cylinder  18  contracts to turn the front end of the cassette  16  slightly toward a return side up to the position b. 
     As a result, the bend of the leading edge of the old plate W 2  is reliably withdrawn from the plate cylinder  3 . Upon subsequent expansion of the air cylinder  44 , the old plate W 2  is completely accommodated into the guide plate  41  of the cassette  16  (see a two-dot chain line in FIGS.  4 ( a ) to  4 ( c )). After removal of the old plate W 2 , an automatic mounting action for a new plate W 1  is started at the position b. 
     That is, as shown in FIGS.  4 ( a ) to  4 ( c ), the air cylinder  34  is expanded to project the leading edge of the new plate W 1  from the cassette  16  via the holding member such as the suction pads  30  (see FIGS.  4 ( a ) to  4 ( b )). At this time, the moving guide  41   a  rests at a waiting position indicated by a two-dot chain line in FIG.  4 ( b ) because of the expansion of the air cylinder  43 . 
     On this occasion, the new plate W 1  is deformed, by setting the lengths of the long and short links  33   a  and  33   b  as well as the stroke amount of the air cylinder  34 , such that the leading edge bend  35  of the new plate W 1  (the front end portion of the plate at an acute bending angle) and the gripping support side surface  36   a  of the gap  36  of the plate cylinder  3  become nearly parallel to each other at the time of mounting the printing plate. 
     Then, the second air cylinder  18  is expanded again to turn the front end of the cassette  16  from the position b to the position c. As a result, the leading edge bend  35  of the new plate W 1  held by the suction pads  30  is inserted into the plate cylinder  3  (see FIGS.  4 ( b ) to  4 ( c )). 
     On this occasion, the leading edge bend  35  of the new plate W 1  and the gripping support side surface  36   a  of the gap  36  are nearly parallel to each other. In addition, the fulcrum  14  of the cassette  16  is placed on a line perpendicular to a line of extension of the gripping support side surface  36   a  of the gap  36  to bring the locus of the leading edge bend  35  close to the gripping support side surface  36   a  in a parallel manner. Thus, the leading edge bend  35  is smoothly inserted into the gap  36  without undue force. 
     Then, the sucking action of the suction pads  30  is released, and the plate cylinder  3  is slowly rotated clockwise (in a direction in which the new plate W 1  is delivered from inside the cassette  16 ), whereby the new plate W 1  is wound around the plate cylinder  3 . When the new plate W 1  is entirely delivered from the cassette  16  and completely wound around the plate cylinder  3 , the winding rod of the plate cylinder  3  is tightened by operation of the lever disposed in the end face portion of the plate cylinder  3 . 
     After mounting of the new plate W 1 , the second air cylinder  18  is contracted, and then the third air cylinder  21  is contracted again to retract the cassette  16  slightly relative to the moving frame  15 . Afterwards, the first air cylinder  17  is contracted to turn and restore the front end of the cassette  16  to the position a. 
     The actions of the first to third air cylinders  17 ,  18  and  21  in the loader  10  and the actions of the air cylinders  34 ,  43  and  44  in the cassette  16  that have been performed up to this point may be carried out at the push of the button by the operator, or by sequential control relying on the loader and cassette controller. 
     Then, the motor  26  is started again at the operator&#39;s push of the button, or by sequential control by the loader controller. Consequently, the loader  10  travels along the rail  8  of the linear guide by the action of the rack  9  and the pinion  27 , and is returned to the waiting position outside the printing press. 
     Then, the printing press is run to resume printing. In the loader  10 , on the other hand, the discharged old plate W 2  is withdrawn from the cassette  16 , and a new plate W 1  to be used next time is set in the cassette  16 . 
     According to the present embodiment as described above, the loader  10  is placed in await state at the waiting position (outside the printing press) on an operating side of the printing press when the plate is not replaced. Compared with a wait on a drive side of the printing press under an untidy work environment, therefore, the operator needs less movement, and can move more easily, so that the working efficiency is improved. 
     Mounting of the new plate W 1  and dismounting of the old plate W 2  are performed by the same action, i.e., turning of the cassette  16 . Thus, the first to third air cylinders  17 ,  18  and  21  can be shared, thus simplifying the plate replacing system. 
     The cassette  16  has an intermediate stopping position (position b). Thus, the gripping withdrawal of the old plate W 2  as well as the gripping insertion of the new plate W 1  can be performed by a minimum, necessary turning (pivoting) action, so that the operating time can be shortened. 
     During movement of the holding member such as suction pads  30  from the waiting position to the inserting position, the new plate W 1  can be deformed, by setting the lengths of the long and short links  33   a  and  33   b  as well as the stroke amount of the air cylinder  34 , such that the leading edge bend  35  of the new plate W 1  and the gripping support side surface  36   a  of the gap  36  of the plate cylinder  3  become nearly parallel to each other at the time of mounting the new plate W 1 . Thus, mounting work can be performed smoothly, without the need to upsize the cassette  16 . Furthermore, the phase of the plate cylinder  3  is the same as the phase of the gripping withdrawal of the old plate W 2 , so that the replacing time can be shortened. 
     In detail, to carry out the mounting work smoothly, a constitution may be conceived in which the leading edge bend  35  of the new plate W 1  is placed in the cassette  16  at an angle parallel to the gripping support side surface  36   a  of the gap  36  (see a two-dot chain line in FIG.  4 ( b )), and moved straightly. With this constitution, the cassette  16  for covering the new plate W 1  must be very large in size. With a constitution in which the new plate W 1  is mounted, in a deformed shape, inside the cassette  16 , and moved parallel, on the other hand, the work of mounting the new plate W 1  to the cassette  16  becomes difficult. 
     According to the above embodiment, the new plate W 1  is deformed from the state of FIG.  4 ( a ) into the state of FIG.  4 ( b ). However, the same effect as in this embodiment can be obtained, even when a mechanism for moving the new plate W 1  from the state of FIG.  4 ( a ) is provided to move it to the position of the new plate W 1  indicated in the two-dot chain line of FIG.  4 ( b ) without deforming it. 
     According to the present invention, there is provided the above-described plate replacing system comprising a cassette capable of accommodating a printing plate and supported so as to be pivotable, the cassette being contactable with and separable from a plate cylinder, and a printing plate moving mechanism provided in the cassette for holding the printing plate and moving the printing plate such that a bent front end surface formed at a leading edge front end portion of the printing plate becomes nearly parallel to a gripping support side surface of a plate cylinder gap. According to this system, mounting and dismounting of the printing plate are both performed by a cassette turning action. Mounting of the printing plate on the plate cylinder is also carried out smoothly without upsizing the cassette. Thus, the plate replacing time can be shortened. Moreover, the sharing of the drive device simplifies the printing press. 
     The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.