Abstract:
The present invention provides a method for operating a sheet-fed offset press so as to reduce the occurrence of spoilage caused by nonuniform printing. In this method, the timing of start of oscillating motion of oscillating rollers is regulated. Also, the present invention provides an oscillation mechanism for a sheet-fed offset press, in which less failure and wear occur, and a smaller force is required to accomplish a changeover from transmission to stoppage of oscillation and vice versa.

Description:
FIELD OF THE INVENTION AND RELATED ART STATEMENT 
     The present invention relates to a method for operating a sheet-fed offset press and, more particularly, to a method for operating a sheet-fed offset press in which an oscillating roller accomplishes an oscillating motion. Also, the present invention relates to an oscillation mechanism for an oscillating roller in an ink supply system for a sheet-fed offset press. 
     First, a method for operating a sheet-fed offset press, which relates to the present invention, will be described. 
     To distribute ink on rollers, some number of ink rollers in an offset press have so far been oscillated in the axial direction of the rollers. For a multi-color sheet-fed offset press in which ink rollers are oscillated, sheets supplied from a sheet-feeder are generally printed in one color at each printing station. Each printing station consists of an ink supply system, a dampening system for supplying water, and a number of rollers. Some of these rollers act as oscillating rollers that serve to distribute ink in the roller-width direction. 
     Many of these oscillating rollers always oscillate by a fixed amount. However, if the oscillating motion of the oscillating rollers continues during the time when printing operation is stopped temporarily for some reason, an ink supply-demand balance between ink transferred to a sheet and ink on the roller, which has been attained during printing operation, is lost undesirably. Specifically, during a steady printing operation, a balance is maintained between the amount of ink supply and the amount of ink transferred to paper sheets such that in printing portions where ink transfers to sheets, the ink supply amount increases, and in non-printing portions where only a small amount of ink transfers to the sheet, the ink supply amount decreases. Therefore, the ink distribution in the axial direction on the rollers is not uniform. However, when the press operation is stopped for some reason, for example, for an error in sheet position setting, if the oscillating rollers continue to be driven, the distribution of ink on the rollers becomes uniform by the distributing effect of the oscillating motion. As a result, when the printing operation is restarted, a number of paper sheets are printed with undesirable nonuniformity until the balanced state maintained before the stoppage of printing operation is achieved again. 
     In recent years, in some offset presses, the oscillation is started and stopped according to the timing of press operation to decrease such spoilage at the start of printing operation. An example of such a press is in Japanese Patent Laid-open Publication No. 11-240139 (No. 240139/1999). In this press, as the printing operation is started, the oscillation of the oscillating roller having a null or minimum amplitude at first is gradually increased, and the amplitude of the oscillating roller reaches a maximum when a form roller is brought into contact with a plate cylinder. In addition, Japanese Patent Publication No. 7-102698 (No. 102698/1995) discloses a printing press in which the oscillation is started or stopped at the same time that a form roller is separated from or is brought into contact with a plate cylinder. 
     Next, a conventional oscillation mechanism for an oscillating roller in an ink supply system for a press will be described. 
     A conventional example of an oscillation mechanism for a form roller, which has been disclosed in the aforementioned Japanese Patent Provisional Publication No. 11-240139 (No. 240139/1999), is explained below with reference to FIG. 9 showing the outline of a general offset press, FIG. 10 showing a oscillation drive system, FIG. 11 showing an essential part of a mechanism for starting and stopping oscillation, and FIG. 12 showing a cross section of FIG.  11 . 
     Referring now to FIG. 9, paper sheets supplied from a sheet-feeder  301  are printed in a printing system  302 , and are stacked and discharged to a sheet discharge section  305 . The multi-color printing system  302  such as an offset press is composed of a plurality of printing units  302   a ,  302   b ,  302   c  and  302   n  provided according to the number of printing colors, and each printing unit include an ink supply system  303  for supplying ink, which is composed of a plurality of rollers, and a dampening system  304  for supplying dampening water. Of these systems, the ink supply system  303  is provided with a plurality of oscillating rollers  306  that oscillate in the axial direction to slidingly rub form rollers in order to distribute ink uniformly in the width direction. 
     FIG. 10 is a system diagram of a drive for oscillating the oscillating rollers  306 . In this drive system, a driving force is transmitted from a crank of an oscillation drive source  307 , which is driven by a drive system  309  for the machine, to an oscillation drive pin  310  provided at the tip end of an oscillation drive lever  311  via a drive link  308 . Also as shown in FIG. 12, the oscillation drive lever  311  oscillates around a pin  312  provided on bearers  318  fixed to a machine frame. An oscillating lever  313 , which oscillates around the pin  312  in the same way, consists of portions  313   a  and  313   b  for driving the oscillating rollers  306  and a portion  313   c  subjected to an oscillating force by the oscillation drive pin  310 . 
     At the end of the oscillating lever  313   a ,  313   b  is provided an oscillation transmitting portion (details thereof is omitted)  317  for transmitting the oscillating force to the shaft end of the oscillating roller  306 . Also, the portion  313   c  is provided with an oscillation drive changeover mechanism  319  that is composed of a change over member  314  engaging with the oscillation drive pin  310  to accomplish a changeover from transmission to stoppage of oscillation and vice versa and a changeover actuator  316  which moves the changeover member  314  to accomplish a changeover from transmission to stoppage of oscillation and vice versa. 
     As shown in FIG. 11, the changeover member  314  is formed with an arcuate elongated hole  315  such that there is a gap large enough for the oscillation drive pin  310  to slide, and the oscillation drive pin  310  is moved by the drive link  308  so that the range of oscillation produced by the oscillation drive lever  311  is not interfered. Thus, as shown in FIG. 12, the changeover member  314  engages with the oscillation lever  313   c  so as to fit to it and be capable of turning around the oscillation drive pin  310 . 
     The changeover member  314  is moved by the actuator  316  or change over the direction of the elongated hole  315  from A to B and vice versa in FIG. 11, by which the oscillation force is transmitted and stopped. Specifically, when the changeover member  314  is made in the state of A by the actuator  316 , the oscillation drive pin  310  oscillated by the oscillation drive lever  311  oscillates only in the elongated hole  315 , so that the oscillation force is not transmitted to the oscillation lever  313 . On the other hand, when the changeover member  314  is made in the state of B, the oscillation force can be transmitted. 
     OBJECT AND SUMMARY OF THE INVENTION 
     In these related arts, the timing of start or stop of oscillation consists of synchronization with the contact of form rollers with the form plate and the start and stop of printing operation. According to a study made by the inventors, it has been found that the timing of start and stop of drive of oscillating rollers described in the related arts is not always optimum. Accordingly, an object of the present invention is to provide a method in which the drive of oscillating rollers is optimized, and spoilage caused by the short-time stoppage of a printing press during operation is minimized. 
     The present invention provides a method for operating a sheet-fed offset press in which an oscillating roller accomplishes an oscillating motion, comprising: a step of receiving a command to stop printing operation; a step of stopping the oscillating motion of the oscillating roller; and a step of separating a form roller from a form plate after a plate cylinder rotates 2 to 7 turns subsequently. 
     Also, the present invention provides a method for operating a sheet-fed offset press in which an oscillating roller accomplishes an oscillating motion, comprising: a step of receiving a command to start printing operation; a step of bringing a form roller into contact with a form plate placed on a plate cylinder; and a step of starting the oscillating motion of the oscillating roller after the plate cylinder rotates 2 to 7 turns subsequently. 
     The method in accordance with the present invention embraces various methods and is not subject to any special restriction if there is provided an oscillating roller such that the oscillating motion thereof can be turned on and off and the amplitude of the oscillating motion can be changed. Also, the drive system of the oscillating roller is not subject to any special restriction. For example, the mechanisms described in the aforementioned Japanese Patent Provisional Publication No. 11-240139 and Japanese Patent Publication No. 7-102698 and preferably a mechanism described below can be utilized to accomplish the oscillating motion of the oscillating roller. 
     As described above, according to the method in accordance with the present invention, the oscillating motion of the oscillating roller in the sheet-fed offset press can be controlled properly. Therefore, when printing operation is restarted after interruption, a proper ink film thickness profile can be formed rapidly, so that the occurrence of spoilage caused by nonuniform printing can be reduced. 
     On the other hand, as is apparent from the above description, for the conventional oscillation mechanism for the oscillating roller, the portions for transmitting an oscillating force from the oscillation drive pin  310  to the changeover member  314  are portions indicated by C 1  and C 2  of FIG. 11, which provides line-to-line contact. Therefore, wear takes place rapidly, and a gap caused by wear produces an impact force when a force is transmitted, which further accelerates wear. Therefore, parts must be replaced early due to wear and breakage. 
     Also, the changeover actuator  316  requires a large force because a difference between the distance L 1  from the turning center of the changeover member  314  to the resistance portion and the distance L 2  from the turning center of the changeover member  314  to the point of application for changeover is small. Therefore, the changeover actuator  316  having a high capacity is needed. Therefore, since the size of the changeover actuator  316  is made large, the size of the whole mechanism increases, so that the efficiency of utilization of tight space is decreased. 
     In view of the above situation, another object of the present invention is to provide an oscillation mechanism for an oscillating roller in which wear of a changeover member for transmitting and stopping an oscillating force is prevented to prolong the life, and the force for changeover is made low to enable a changeover actuator with a low capacity to be used, whereby space saving and low cost are provided, and failure and wear are reduced. 
     To achieve the above object, the present invention provides an oscillation mechanism for an oscillation roller in an ink supply system for a printing press, comprising an oscillating lever which oscillates around a support point with a predetermined angle to give an oscillating force to an oscillating roller and is formed with oscillation drive bearing portions on both sides on the opposite sides of the support point; first and second energizing members which are in contact with the oscillation drive bearing portions to give a pressing force; and a reciprocating drive means for transmitting a pressing turning force in the normal or reverse direction to the first and second energizing members by reciprocating motion, wherein the transmission of oscillation is stopped by the separation of the first energizing member from the oscillation drive bearing portion. 
     According to the above-described configuration, the mechanism for transmitting and stopping an oscillating force consists of the pressing of the energizing member to the oscillation drive bearing portion and the separation of the energizing member from the oscillation drive bearing portion, so that there is nothing that is worn. Therefore, wear and breakage caused by the line-to-line contact as in the case of the related arts can be prevented. 
     Oscillating force transmitting means is characterized in that the first energizing member is pivotally supported by a second support point coaxial with the reciprocating drive means, and the second energizing member is pivotally supported coaxially with the support point of the oscillating lever, whereby the energizing members are turned around the support point of the oscillating lever by an arm connecting the support point of the oscillating lever to the second support point. 
     According to the above-described configuration, a complicated construction such that the changeover member is fitted on the oscillation drive pin as in the case of the related arts is not needed, and a difference between the distance from the turning center to the resistance portion and the distance to the point of application for changeover can be increased. Therefore, changeover can be effected with a small force, so that an actuator with a low capacity can be used, whereby the mechanism can be configured at a low cost. 
     Also, another oscillating force transmitting means is characterized in that the energizing members are reciprocatively driven by an arm which pivotally supports the first energizing member at one end, pivotally supports the second energizing member at the other end on the opposite sides of the support point, and further pivotally supports reciprocating drive means at one end. By this configuration, the mechanism can be configured more simply. 
     Means for separating the first energizing member from the oscillation drive bearing portion is an actuator engaged with the first energizing member. By using such an actuator, the transmission and stoppage of an oscillating force can always be effected. 
     Also, the transmitting portion for transmitting an oscillating force to the oscillating roller is characterized in that the oscillation drive bearing portion and energizing member are brought into face-to-face contact with each other. 
     By the face-to-face contact between the oscillation drive bearing portion and the energizing member, wear etc. of the changeover member brought about in the conventional example is eliminated, so that the oscillation mechanism for the oscillating roller that is less failed and worn can be provided. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic view showing a construction of a printing station for a sheet-fed offset press capable of using a method in accordance with the present invention; 
     FIG. 2 is a schematic view showing a construction of a sheet-fed offset press capable of using a method in accordance with the present invention; 
     FIG. 3 is a flowchart showing a procedure for stopping operation in accordance with one embodiment of a method of the present invention; 
     FIG. 4 is a flowchart showing a procedure for starting operation in accordance with one embodiment of a method of the present invention; 
     FIG. 5 is a schematic system diagram of oscillation drive for an oscillating roller in an ink supply system in accordance with the present invention; 
     FIG. 6 is a configuration view of an embodiment of an oscillation mechanism and oscillation drive changeover mechanism for an oscillating roller in accordance with the present invention; 
     FIG. 7 is another embodiment of an oscillation mechanism in accordance with the present invention; 
     FIG. 8 is still another embodiment of an oscillation mechanism in accordance with the present invention; 
     FIG. 9 is a schematic view showing the outline of a general printing press; 
     FIG. 10 is a system diagram of an oscillation drive; 
     FIG. 11 is a view showing an essential part of a mechanism for starting and stopping an oscillating roller relating to the present invention; and 
     FIG. 12 is a sectional view of FIG.  11 . 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     FIG. 1 shows an example of a printing station for a sheet-fed offset press to which a method for driving an oscillating roller in accordance with the present invention can be applied. The arrangement of a plurality of such printing stations can constitute a multi-color sheet-fed offset press as shown in FIG.  2 . 
     Referring to FIG. 1, each of the printing stations  1  has a plate cylinder  3 , a rubber blanket cylinder  4 , and a back impression cylinder  5  as shown in the figure. Further, each of the printing stations  1  includes an ink supply system  6  and a dampening system  7 . Such an offset press  1  is controlled by an electronic controller (not shown) equipped with a microprocessor. An operator can control the press through this electronic controller. The electronic controller controls the printing station  1 ; specifically, it controls not only the on/off operation of the plate cylinder  3 , the rubber blanket cylinder  4 , and the back impression cylinder  5 , but also the ink supply system  6  and the dampening system  7 . 
     In FIG. 1, printing ink is stored in an ink fountain  12  consisting of an ink tray  10  and an ink tray roller  11 . A quantity regulating device  13 , which is constituted of the arrangement of a plurality of regulating members each having a fixed width and lined up in the width direction of the press, is disposed so as to be in close contact with the ink tray roller  11 , so that the quantity of supplied ink can be regulated by each width of the regulating member. An oscillating transfer roller  14  transfers printing ink from the ink tray roller  11  to a first oscillating roller  15 . The ink is transferred with different ink layer thicknesses in the transverse direction with respect to the printing direction for each width of individual regulating member. The ink supply system further includes second, third, and fourth oscillating rollers  16 ,  17  and  18 , a first form roller  19  for applying ink to a form plate  23  attached onto the surface of the plate cylinder  3 , and other form rollers  20 ,  21  and  22 . The dampening system  7  includes a dampening water fountain  24  on a tray, and a dampening roller  25  partially touches water in the fountain  24 . A quantity regulating roller  26  is disposed in a state of touching the dampening water fountain  24 . The dampening roller  25  and the quantity regulating roller  26  can be driven at varying speeds. Thereby, the feed quantity of dampening water can be changed, for example, so as to match the rotational speed of the roller group. The dampening water is transmitted to the form plate  23  and an intermediate roller  29  via a dampening roller  27  (which may also act as a form roller) that is in contact with the quantity regulating roller  26 . 
     The aforementioned electronic controller carries out control of the whole printing machine during the operation of the printing machine including the start time and stop time, and keeps a proper quantity of dampening water. The ink supply system  6  and the form plate  23  are dampened. The electronic controller controls the positions of rollers, especially the touch and withdrawal of the oscillating rollers  15 ,  16 ,  17  and  18 , and the distribution of dampening water in each step. When the printing operation is stopped, all of the rollers  19 ,  20 ,  21 ,  22  and  27  for applying ink and dampening water are withdrawn from the form plate  23 . When the printing operation is restarted, the dampening roller  27  is brought into contact with the form plate  23  by the controller, by which dampening of the form plate  23  and the ink supply system  6  is executed via the intermediate roller  29 . After this preliminary dampening, the oscillating rollers  15 ,  16 ,  17  and  18  are brought into contact with the form plate  23 , by which ink film forming is performed. In the dampening and ink supplying operations, the oscillating rollers  15 ,  16 ,  17  and  18  perform a reciprocating straight motion in the axial direction to properly level the profile of ink supplied from an ink supply unit  12 , by which uniform printing can be accomplished. In the method of the present invention, the driving of the oscillating rollers  15 ,  16 ,  17  and  18  is controlled in the optimum manner. 
     During the time when printing is performed by the offset press, a necessity for temporarily stopping the printing operation arises due, for example, to shifted positioning of paper sheets. After instructions to stop the printing operation are given, the controller issues instructions to withdraw the form rollers  19 ,  20 ,  21 ,  22  and  27  from the form plate  23 . According to the present invention, at this time, the reciprocating straight motion in the axial direction (transverse oscillating motion) of the oscillating rollers  15 ,  16 ,  17  and  18  are first stopped, or the amplitude of this motion is reduced. Subsequently, after the plate cylinder  3  (form plate  23 ) has rotated several turns, preferably 2 to 7 turns and more preferably 3 to 5 turns, the form rollers  19 ,  20 ,  21 ,  22  and  27  (the form roller  27  also acts as a dampening roller) are actually withdrawn from the form plate  23 . The reason for this is that by stopping the transverse oscillating motion before the stoppage of printing operation on an actual sheet, ink is to be supplied from the ink supply unit  12  to the roller group without being leveled in the axial direction of the rollers. Therefore, it is preferable to determine the time when the transverse oscillating motion of the oscillating rollers  15 ,  16 ,  17  and  18  is performed before the withdrawal of the form rollers, according to the distance on the rollers from the ink supply unit  12  to the form plate  23 . Thereupon, when the printing operation is stopped, a profile of ink film thickness not leveled so much remains on the surfaces of rollers of the roller group, especially on the surfaces of the form rollers  19 ,  20 ,  21 ,  22  and  27 . Thereby, the amount of spoilage caused by nonuniform printing at the time when the printing operation is restarted can be reduced. 
     Further, when the printing operation is started, the operator issues instructions to bring the form rollers  19 ,  20 ,  21 ,  22  and  27  into contact with the form plate  23 . In response to this, the form rollers are brought into contact upon instructions from the controller. At this time, after the form rollers are brought into contact, the transverse oscillating motion of the oscillating rollers  15 ,  16 ,  17  and  18  is started after the plate cylinder  3  has been rotated several turns, preferably 2 to 7 turns and more preferably 3 to 5 turns. By delaying the start of transverse oscillating motion of the oscillating rollers  15 ,  16 ,  17  and  18  from the contact of the form rollers, the profile of film thickness of ink on the rollers leveled by the transfer between rollers performed during the stoppage of printing operation can be prevented from being uniformed unnecessarily by the transverse oscillating motion of the oscillating rollers  15 ,  16 ,  17  and  18 . Therefore, a proper ink film thickness profile can be attained rapidly. 
     FIGS. 3 and 4 show an example of a flow of control procedure for a printing machine in accordance with the method of the present invention. Referring to FIG. 3, when a command to start the printing operation is received ( 101 ), the dampening roller  27  (also acts as a form roller) is turned on at fixed timing on the instructions of the controller ( 102 ). Then, after some delay, preferably after a delay of about 1 to 2 turns of the plate cylinder  3 , the form rollers  19 ,  20 ,  21 ,  22  and  27  are brought into contact with the plate cylinder  3  ( 103 ). Subsequently, with a time interval of several turns of the plate cylinder  3 , the transverse oscillating motion of the oscillating rollers  15 ,  16 ,  17  and  18  is turned on ( 104 ). At this time, the amplitude of the transverse oscillating motion may be increased immediately to the ordinary operation amplitude, or may be increased gradually to the ordinary amplitude. Also, the amplitude of the transverse oscillating motion can be increased from the state of complete stoppage or from the state of operation at a small amplitude to the ordinary amplitude. After that, at an interval of 1 to 3 turns of the plate cylinder  3 , an operation of bringing the rubber blanket cylinder  4  into contact with the plate cylinder  3  and an operation of bringing the back impression cylinder  5  into contact with the rubber blanket cylinder  4  are performed substantially at the same time ( 105 ). Following these operations, the feed of sheets is started, and printing operation is actually started ( 106 ). Subsequently, a steady operation is performed ( 107 ). 
     As in an example shown in FIG. 4, when a command to stop the printing operation is received ( 201 ), the transverse oscillating motion of the oscillating rollers  15 ,  16 ,  17  and  18  is stopped or reduced upon instructions from the controller ( 202 ). Then, with a time interval of several turns of the plate cylinder  3 , preferably at a time interval of 3 to 5 turns, the form rollers  19 ,  20 ,  21 ,  22  and  27 , the rubber blanket cylinder  4 , and the back impression cylinder  5  each are moved to the withdrawal position, by which the contacting state is released ( 203 ). At this time, the dampening roller  25  can also be stopped at the same time, or it can also be stopped after a delay of 1 to 3 turns of the plate cylinder  3 . The feed of sheets can also be stopped at the same time ( 204 ). 
     Next, an embodiment of an oscillation mechanism for the oscillating rollers in the ink supply system for the printing press in accordance with the present invention will be described exemplarily in detail with reference to FIGS. 5 to  12 . The dimensions, material, relative arrangement of components described in this embodiment do not limit the scope of the present invention, but represent only an explanatory example unless especially noted. 
     FIG. 5 is a system diagram of an oscillation drive for the oscillating roller in the ink supply system for the printing press in accordance with the present invention. FIG. 6 is a configuration view of the oscillation mechanism and oscillation drive changeover mechanism. In the figures, the same reference numerals are applied to the same elements as those of the previously mentioned related art. 
     Referring to FIGS. 5 and 6, an oscillation drive source  307  is rotated by a rotational force transmitted from a machine drive system  309 , and a drive link  308  transmits an oscillating force via a crank or the like. Of two types of an oscillation drive lever  321  and an oscillating lever  322  that turn around a pin  312  supported on a bearer  318  fixed to a machine frame, the oscillating lever  322 , consisting of balance-shaped oscillating levers  322   a  and  322   b  disposed at about 180 degrees with respect to the pin  312 , is provided with an oscillation transmitting portion  317  at each end to oscillate an oscillating roller  306 . 
     The oscillating lever  322   a ,  322   b  has an oscillation drive bearing portion  323 ,  324 , respectively, so as to receive an oscillating force from an oscillation drive transmitting portion  325  of an oscillation drive lever  321   b  and an oscillation drive transmitting portion  326  of a changeover member  327 , which are in face-to-face contact with the oscillation drive bearing portion  323 ,  324 . At the other end of the oscillation drive lever  321  is provided an oscillation drive pin  328  to receive an oscillating force from the drive link  308 . The oscillation drive lever  321 , which is oscillated around the pin  312  by receiving an oscillating force from the drive link  308 , has a projecting arm  321   b.  The distal end of the arm  312   b  is in face-to-face contact with the oscillation drive bearing portion  323  of the oscillating lever  322   a  so as to transmit a force in one direction (a force in the left direction in FIG. 5) of the oscillating force. 
     Also, the changeover member  327 , which turns around the oscillation drive pin  328 , is provided with the oscillation drive transmitting portion  326  at one end. The oscillation drive transmitting portion  326  comes into contact with and separates from the oscillation drive bearing portion  324  of the mating oscillating lever  322   b  so as to transmit a force in the other direction (a force in the right direction in FIG. 5) transmitted to the oscillation drive pin  328 . The changeover member  327  is turned around the oscillation drive pin  328  by the action of a changeover actuator  316 . One end of the changeover actuator  316  is supported on the oscillation drive lever  321 , and the other end thereof is engaged with the changeover member  327 . The changeover actuator  316  may be driven in both directions, or may be driven only in one direction and the changeover member  327  may be moved in the other direction by using a spring  320  shown in FIG.  6 . 
     The oscillation drive transmitting portion  326  provided at one end of the changeover member  327  is formed with an arcuate face having a radius R with the oscillation drive pin  328 , which is the turning center, being the center or a face approximate to the arcuate face at the distal end thereof. The face of the oscillation drive bearing portion  324  of the oscillating lever  322   b , which is the mating face of the oscillation drive transmitting portion  326 , has a shape such as to be in face-to-face contact with the face of the oscillation drive transmitting portion  326  of the changeover member  327 . 
     Next, the operation of the oscillation mechanism will be described with reference to FIG.  6 . In the case where the oscillation drive transmitting portion  326  of the changeover member  327  is in contact with the oscillation drive bearing portion  324  of the oscillating lever  322   b  as shown in FIG. 6, when the drive link  308  moves downward in the figure, the oscillation drive lever  321  and the changeover member  327  move together in the downward direction, by which the oscillation drive bearing portion  324  of the oscillating lever  322  is pressed. Therefore, the oscillating lever  322   b  moves to the left in the figure with the pin  312  being the center, the not illustrated oscillating roller  306  oscillates to the left, and the oscillating roller  306  connected to the oscillating lever  322   a  at the other end moves to the right. 
     When the drive link  308  moves inversely in the upward direction in the figure, the oscillation drive transmitting portion  325  of the oscillation drive lever  321   b  presses the oscillation drive bearing portion  323  of the oscillating lever  322   a . Therefore, the oscillating lever  322   a  moves to the left in the figure with the pin  312  being the center, the not illustrated oscillating roller  306  oscillates to the left, and the oscillating roller  306  connected to the oscillating lever  322   b  at the other end moves to the right. A similar operation is repeated by the up-and-down movement of the drive link  308 , so that the oscillating rollers  306  are oscillated from side to side. 
     At this time, when a command to stop the oscillation of the oscillating rollers is given by the not illustrated controller, the command is transferred to the actuator  316  to operate the actuator  316 , so that the changeover member  327  is pulled to the side of the actuator  316 , and therefore the oscillation drive transmitting portion  326  comes off from the oscillation drive bearing portion  324  of the oscillating lever  322   b.  Therefore, even if the drive link  308  moves downward in the figure, although the oscillation drive lever  321  moves downward, there is nothing that presses the oscillation drive bearing portion  324  of the oscillating lever  322 , so that the oscillating lever  322   b  does not move. 
     When the drive link  308  moves inversely in the upward direction in the figure, the oscillation drive transmitting portion  325  of the oscillation drive lever  321   b  presses the oscillation drive bearing portion  323  of the oscillating lever  322   a.  Therefore, although the oscillating lever  322   a  moves to the left in the figure with the pin  312  being the center, there is nothing that presses the oscillation drive bearing portion  324  of the oscillating lever  322 , as described above, so that the oscillating lever  322  does not return in the reverse direction. Thereupon, the oscillation of the oscillating rollers  306  stop at this time. 
     The above is a description of the operation of the oscillation mechanism for the oscillating rollers in accordance with the present invention. As can be seen from the above description, the oscillating force transmitting portions, that is, the oscillation drive transmitting portion  325 ,  326  and the oscillation drive bearing portion  323 ,  324  are in face-to-face contact with each other, so that less wear occurs in the transmitting portion. Therefore, there is no influence such as an impact force caused by an increased gap. For this reason, the oscillation mechanism in accordance with the present invention can be used steadily for a long period of time without less maintenance, and the cost for remedying wear is low. Also, the vibrations of the printing press caused by the impact force are small, so that high printing quality can be obtained. 
     Also, as shown in FIG. 6, since the distance L 5  to the point of application of the changeover actuator  316  is far larger than the distance L 4  to the resistance force occurrence potion, the output of the actuator  316  can be made low, and therefore the shape thereof can be made small. Therefore, the efficiency of utilization of tight space is enhanced, so that the size of the whole mechanism can be made small. 
     Although the shape of the oscillation drive lever  321   b  is made an arm shape in the above description, the shape thereof is not limited to this. For example, as shown in FIG. 7, the shape thereof may be made a triangular shape, and the oscillation drive transmitting portion  325  and the oscillation drive bearing portion  323  may be wider. Also, although the oscillation drive transmitting portion  326  of the changeover member  327  and the oscillation drive bearing portion  324  are substantially at right angles to the lengthwise direction of the changeover member  327  as shown in FIG. 6 in the above description, they may have a shape that coincides with the outside shape of the oscillating lever  322   b  as shown in FIG.  7 . In this case, when the changeover member  327  returns to the original position on instructions to restart oscillation after the changeover member  327  is separated from the oscillating lever  322   b  on instructions to stop oscillation drive, even if the oscillating lever  322   b  lies at any position, the changeover member  327  can return easily. Also, although the oscillation drive transmitting portion  325 ,  326  and the oscillation drive bearing portion  323 ,  324  are face-to-face contact with each other in the above description, one of the two may be of a roller type. 
     Also, the mechanism itself composed of the oscillation drive lever  321  and the changeover member  327  is not limited to the mechanism shown in FIG. 6, and it may have a parallelogram shape as shown in FIG.  8 . In FIG. 8, reference numeral  340  denotes the oscillation drive lever, and  341  denotes the changeover member. The oscillation drive lever  340  and the changeover member  341  are configured so that the oscillation drive lever  340  is fixed to one end of an arm  342  pivotally supported by a pin  344  of the bearer  343 , and the changeover member  341  engages with the actuator  316  and is pivotally supported by one end of the arm  342 . 
     The drive link  308 , which is pivotally supported by one end of the arm  342 , transmits an oscillation drive force. In the state shown in FIG. 8, the oscillation drive lever  340  and the changeover member  341  are in contact with the oscillating lever  322 , so that when the drive link  308  reciprocates transversely in the figure, the arm  342  and the oscillating lever  322  move in exactly the same manner. Accordingly, the oscillating rollers  306  connected to the oscillating lever  322  also move in exactly the same manner. 
     As in the case of the above description, when instructions to stop oscillation are given, the actuator  316  is operated, so that the changeover member  341  comes off from the oscillating lever  322 . As a result, the movement of the drive link  308  is not transmitted to the oscillating lever  322 . It is to be noted that the drive link  308  may be pivotally supported on the changeover member side of the arm  342 , not at the position shown in FIG.  8 . 
     In the case of the embodiment shown in FIG. 8, the contact point of the oscillating lever  322  and the oscillation drive lever  340  is shifted by oscillation. To accommodate this shift, for example, the configuration may be such that the oscillation drive lever  340  is pivotally supported coaxially with the drive link  308 , and a guide member for holding the oscillation drive lever  340  is fixed to the arm  342 , by which the oscillation drive lever  340  is prevented from coming off from the contact point of the oscillating lever  322 . Also, inversely, the drive link  308  may be extended to be used as an energizing member for the oscillating lever  322 . In this case, the drive link  308  and the arm  342  may be pivotally fixed to each other with a play provided between them.