JP4813100B2 - Sheet-fed printing machine paper discharge device - Google Patents

Description

  The present invention relates to a paper discharge device for a sheet-fed printing press that receives a driving force from a rotational drive unit of a cylinder of a printing press to lower a paper discharge stand.

  Conventionally, this type of paper discharge device is driven from a paper discharge table on which sheets printed on the cylinder of the printing machine are sequentially stacked, and a rotation drive unit (generally a motor and a gear train) of the cylinder of the printing machine. A sheet discharge table driving unit that receives the force to lower the sheet discharge table, a driving force transmission unit that transmits a driving force from the rotation driving unit to the sheet discharge table driving unit, and a driving force transmitted to the driving force transmission unit And a switching unit that selectively switches between a connection state and a blocking state in which the driving force is blocked. Since the printed sheets are sequentially placed on the sheet discharge table, the uppermost sheet that is positioned at the top of the sheets stacked on the sheet discharge table should not exceed a predetermined height. There is a need. Therefore, when the uppermost sheet reaches a predetermined height, the switching unit connects the driving force transmitting unit, whereby the driving force is transmitted from the rotation driving unit to the discharging table driving unit, and the discharging table starts to descend. Then, when a predetermined time elapses after the discharge table starts to descend, the switching unit cuts off the driving force, and thus the discharge table stops at that position. As described above, each time the uppermost sheet reaches a predetermined height, the switching unit sets the driving force transmission unit to the connected state and sets the cut-off state after a predetermined time has elapsed.

  However, in the conventional paper discharge device, the connection time of the switching unit, which is performed every time the uppermost sheet reaches a predetermined height, is always constant. In other words, since the switching unit is always set so that the driving force transmission unit is connected and the discharge tray is lowered for a certain time regardless of the rotation speed of the cylinder of the printing press, that is, the printing speed, There was a problem.

  In other words, when the rotational speed of the cylinder of the printing press is low, the speed at which the paper discharge table drive unit receiving the driving force from the rotation drive unit lowers the paper discharge table also decreases, and the discharge that is lowered during one connection time. The amount of descent of the paper table (descent distance) is also reduced. Accordingly, the number and frequency of the switching unit switching the driving force transmission unit between the connected state and the disconnected state increase as a result. When printing a predetermined number of sheets (for example, 10,000 sheets) in one printing operation, the predetermined number of sheets are finally placed on the paper discharge table, but printing is performed at a low speed. As a result, the amount of lowering per one connection time of the paper discharge tray is small, and as a result, the number of times of switching of the switching unit during one printing operation is increased. Thus, when the frequency of switching in the switching unit increases, the durability of the switching unit becomes a problem, and this becomes more conspicuous as the sheet used is thicker.

  Conversely, when the rotation speed of the cylinder of the printing press is high, the speed at which the paper discharge table drive unit lowers the paper discharge table also increases and the amount of descent per connection time also increases. Since the uppermost paper on the top is lowered too much at a time and the drop distance becomes long, there is a problem that the position (paper alignment) accuracy at the time of paper discharge to the paper discharge tray tends to deteriorate.

  Therefore, the present invention provides a sheet-fed printing press having a switching unit that selectively switches a driving force transmission unit that transmits a driving force from the cylinder of the printing machine between a connected state and a blocked state. It is an object to improve durability and accuracy of paper alignment.

The present invention has been made to solve the above-described problems, and a sheet discharge device for a sheet-fed printing press according to the present invention includes a sheet discharge table on which sheets printed on a cylinder of the printing press are sequentially stacked. A paper discharge table drive unit that receives a driving force from the rotation drive unit of the cylinder of the printing press and lowers the paper discharge table; a drive force transmission unit that transmits the drive force from the rotation drive unit to the paper discharge table drive unit; A switching unit that selectively switches the driving force transmission unit between a connection state in which the driving force is transmitted and a blocking state in which the driving force is interrupted; Discharge of sheet-fed printing press in which the switching unit moves down with the driving force transmission unit connected and the paper discharge table descends, and the switching unit shuts off the driving force transmission unit after a predetermined connection time and the paper discharge table stops in the device, the connection time per single switching unit, when the rotation speed of the barrel is equal to or higher than the reference speed The first connection time, if the rotation speed of the barrel is less than the reference speed, characterized in that a second connection time longer than the first connection time.

In the paper discharge device configured as described above, the switching unit connects the driving force transmission unit to transmit the driving force from the rotation driving unit to the paper discharge table driving unit, and the discharge table starts to descend. After the connection time elapses, the switching unit shuts off the driving force transmission unit to cut off the driving force and the lowering operation of the paper discharge table is completed. It is not constant. That is, when the cylinder rotation speed is higher than the reference speed, the first connection time is set. When the cylinder rotation speed is lower than the reference speed, the second connection time is set longer than the first connection time. Accordingly, when the rotational speed of the cylinder is equal to or higher than the reference speed, the connection time per time is shortened, and when the rotational speed of the cylinder is smaller than the reference speed, the connection time is increased. In this case, since there are only two connection times of the first and second connection times, there is an advantage that the control of the connection time according to the rotational speed of the cylinder can be simplified.

  In addition, as described above, the first and second connection times may be used, but in at least one of the case where the cylinder rotation speed is equal to or higher than the reference speed and the case where the cylinder rotation speed is lower than the reference speed, The connection time may be gradually shortened according to the increase in the rotation speed of the cylinder, or the connection time may be lengthened according to the decrease in the rotation speed of the cylinder. In this case, for example, even if the rotation speed of the cylinder is within the reference speed or higher, the connection time is gradually shortened as the rotation speed of the cylinder increases. It is possible to suppress a change in the descending amount of the table. Of course, the connection time may be shortened according to an increase in the rotation speed of the cylinder in both cases where the rotation speed of the cylinder is equal to or higher than the reference speed and where the rotation speed of the cylinder is smaller than the reference speed.

  The sheet discharge device for a sheet-fed printing machine according to the present invention is configured to generate a driving force from a sheet discharge table on which sheets printed on the cylinder of the printing machine are sequentially stacked and a rotation driving unit of the cylinder of the printing machine. A receiving tray driving unit that receives and lowers the discharging tray, a driving force transmitting unit that transmits driving force from the rotation driving unit to the discharging table driving unit, and a connection state in which the driving force is transmitted to the driving force transmitting unit And a switching unit that selectively switches between a cut-off state in which the driving force is cut off, and each time the uppermost sheet on the paper discharge tray reaches a predetermined height, the switching unit connects the driving force transmission unit and discharges paper. In a paper discharge device of a sheet-fed printing press in which the base is lowered and the switching unit shuts off the driving force transmission unit after a predetermined connection time and the paper discharge base stops, the switching unit according to an increase in the rotation speed of the cylinder The connection time per time is gradually shortened.

  In the paper discharge device configured as described above, the switching unit connects the driving force transmission unit to transmit the driving force from the rotation driving unit to the paper discharge table driving unit, and the discharge table starts to descend. After the connection time elapses, the switching unit shuts off the driving force transmission unit to cut off the driving force and the lowering operation of the paper discharge table is completed. It is not constant. That is, the connection time per time becomes shorter as the rotational speed of the cylinder increases. Accordingly, the connection time is shortened as the rotational speed of the cylinder is increased, and conversely, the connection time is increased as the rotational speed of the cylinder is decreased.

  In particular, it is preferable to increase / decrease the connection time according to the rotation speed of the cylinder so that the amount by which the paper discharge tray descends during a single connection time is constant, thereby suppressing variations in the sheet fall distance. , The accuracy of paper alignment is further increased.

  The sheet discharge device for a sheet-fed printing machine according to the present invention is configured to generate a driving force from a sheet discharge table on which sheets printed on the cylinder of the printing machine are sequentially stacked and a rotation driving unit of the cylinder of the printing machine. A receiving tray driving unit that receives and lowers the discharging tray, a driving force transmitting unit that transmits driving force from the rotation driving unit to the discharging table driving unit, and a connection state in which the driving force is transmitted to the driving force transmitting unit And a switching unit that selectively switches between a cut-off state in which the driving force is cut off, and each time the uppermost sheet on the paper discharge tray reaches a predetermined height, the switching unit connects the driving force transmission unit and discharges paper. In a paper discharge device for a sheet-fed printing press in which the base is lowered and the switching unit shuts off the driving force transmission unit and stops the paper discharge table, the switching unit is driven each time the driving force transmission unit is connected. When the number of rotations of the cylinder from the start of force transmission reaches a reference number, the driving force transmission unit is cut off.

  In the sheet discharge device of the sheet-fed printing press having the above configuration, the switching unit connects the driving force transmitting unit to the connected state so that the driving force is transmitted from the rotation driving unit to the sheet discharging table driving unit and the sheet discharging table Is started, and the switching unit shuts off the driving force transmission unit to cut off the driving force and the lowering operation of the paper discharge table ends. Then, after the switching unit puts the driving force transmission unit in the connected state, when the number of rotations of the cylinder from the start of transmission of the driving force reaches the reference number, the switching unit sets the driving force transmission unit in a shut-off state and discharges the paper tray. Stop. Therefore, even if the cylinder rotation speed is large or small, the sheet discharge table stops when the number of rotations of the cylinder reaches the reference number. The amount by which the paper discharge platform descends in the meantime is always constant.

As described above, in the sheet delivery of a sheet-fed printing press according to the present invention, the connection time per single switching unit, the first connection time when the rotational speed of the cylinder is equal to or higher than the reference speed When the cylinder rotation speed is lower than the reference speed, the second connection time is longer than the first connection time. Therefore, when the cylinder rotation speed is higher than the reference speed, the connection time is constant. Thus, the amount of descent during one connection time can be reduced as compared with the conventional one, and the sheet fall distance is reduced as compared with the conventional one. Also, when the rotational speed of the cylinder is smaller than the reference speed, the amount of descent during one connection time can be increased and the switching frequency of the switching unit is reduced compared to the conventional one in which the connection time is constant. The durability of the switching part is improved.

  Further, in the sheet discharge device of the sheet-fed printing press according to the present invention, the connection time per switching unit is shortened according to the increase in the rotation speed of the cylinder, so that when the rotation speed of the cylinder is high The amount of descent during one connection time can be reduced as compared with the conventional case, and the paper alignment accuracy of the paper discharge can be improved as compared with the conventional case. In addition, when the rotational speed of the cylinder is low, the amount of descent during one connection time can be increased as compared with the conventional case, and the durability of the switching portion can be improved.

  Further, in the sheet discharge device of the sheet-fed printing press according to the present invention, every time the switching unit places the driving force transmission unit in the connected state, the number of rotations of the cylinder from the start of the driving force connection reaches the reference number. Since the drive force transmission part is shut off and the paper discharge table is stopped, the amount of lowering of the paper discharge table in a single connection of the switching unit is always constant regardless of the rotation speed of the cylinder. It is possible to improve the paper alignment accuracy of the discharged paper and improve the durability of the switching unit.

Hereinafter, an embodiment of a sheet discharge device for a sheet-fed printing press according to the present invention will be described with reference to the drawings.
As shown in FIG. 1, the paper discharge device according to the present embodiment includes a paper discharge tray 1 on which sheets printed on a cylinder of a printing machine (not shown) are sequentially stacked, and a rotation driving unit ( A paper discharge table driving unit 2 that lowers the paper discharge table 1 by receiving a driving force from a not-shown driving force, a driving force transmission unit 3 that transmits the driving force of the rotational driving force to the paper discharge table driving unit 2, and the driving The switching unit 4 that selectively switches the force transmission unit 3 between a connection state in which the driving force is transmitted and a blocking state in which the driving force is interrupted, and the uppermost paper 5 on the paper discharge tray 1 has reached a predetermined height. And a control unit 7 for controlling the switching unit 4. This will be described in detail below.

  The driving force transmission unit 3 transmits the driving force of the rotation driving unit to the paper discharge table driving unit 2 through a horizontally extending lateral link 30 connected to a rotation driving unit of a trunk (not shown). A lower end of an oblique link 31 extending obliquely is rotatably connected to one end of the horizontal link 30, and an upper end of the oblique link 31 swings up and down around a horizontal axis 32. One end of the link 33 is rotatably connected. Since the horizontal link 30 reciprocates in the vertical direction while reciprocating in the left-right direction in the figure in conjunction with the rotation of the trunk, the oblique link 31 reciprocates in the direction of arrow A in the figure as the horizontal link 30 reciprocates. The swing link 33 swings within a predetermined angle range up and down like a seesaw in the direction of arrow B in the figure with the shaft 32 as the center. The center part of the swing link 33 is supported by a shaft 32, and a claw 34 is provided at the other end located on the opposite side of the shaft 32. The base end portion of the claw 34 is rotatably connected to the swing link 33, and the tip end portion of the claw 34 is biased toward the shaft 32 of the swing link 33 by a torsion spring 35 as a biasing means. A ratchet 36 having a tooth portion meshing with the claw 34 formed on the outer peripheral surface is rotatably supported on the shaft 32. When the claw 34 is engaged with the ratchet 36, the ratchet 36 rotates counterclockwise by a predetermined angle when the claw 34 rotates together with the swing link 33 counterclockwise in FIG. Further, a first gear 37 that rotates integrally with the ratchet 36 is provided on the shaft 32, and a second gear 38 is engaged with the first gear 37. A bevel gear 39 that rotates integrally with the second gear 38 is provided coaxially. The above is the driving force transmission unit 3.

  The sheet discharge table drive unit 2 that operates in synchronization with the rotation of the cylinder when the drive force is transmitted from the rotation drive unit by the drive force transmission unit 3 includes a worm 20 that extends in the horizontal direction, and is provided at one end of the worm 20. The driving force is transmitted by the bevel gear 21 provided being engaged with the bevel gear 39 of the driving force transmission unit 3. A sprocket 22 is provided at the other end of the worm 20 and is connected to an upper sprocket 23 that can be manually rotated by a chain 24. A worm wheel 25 is meshed with the worm 20, and a sprocket 26 is coaxially provided so as to rotate integrally with the worm wheel 25. A chain 27 is wound around the sprocket 26, and the paper discharge platform 1 is connected to one end of the chain 27.

  Next, the configuration of the switching unit 4 that transmits or interrupts the driving force from the rotation driving unit to the paper discharge table driving unit 2 will be described. The switching unit 4 moves the claw 34 close to the ratchet 36 when the driving force transmission unit 3 is in the transmission state, and engages both, and when the driving force transmission unit is in the cutoff state, the switching unit 4 It is intended to be separated from the ratchet 36. That is, the switching unit 4 includes a solenoid 40 that is ON / OFF controlled by the control unit 7. A link 42 is connected to the main shaft 41 of the solenoid 40, and one end of a substantially U-shaped link 43 is connected to the lower end of the link 42. The link 43 is pivotally supported by a shaft 44 at the center thereof and swings like a seesaw about the shaft 44. However, the solenoid 40 is turned off and the main shaft 41 moves in the direction of arrow C, so that it is shown in FIG. When positioned below as indicated by the dotted line, the link 43 rotates counterclockwise in the drawing and presses the claw 34 at the other end to release it from the ratchet 36. Conversely, when the solenoid 40 is turned on and the main shaft 41 moves in the direction of arrow D and is positioned upward as shown by the solid line in FIG. 1, the link 43 rotates clockwise and is urged by the biasing force of the torsion spring 35. The claw 34 meshes with the ratchet 36. The link 43 is urged counterclockwise in the figure by a coil spring 45 as urging means.

  The control unit 7 that controls the operation of the switching unit 4 receives a signal from the sensor 6 so that the uppermost paper 5 on the paper discharge tray 1 does not exceed a predetermined height, and turns on the switching unit 4 to rotate the cylinder. The switching unit 4 is turned off based on the speed. That is, when the control unit 7 turns on the solenoid 40, the driving force is transmitted to start the lowering operation of the discharge table 1, and when the control unit 7 turns off the solenoid 40, the driving force is cut off and the discharge table 1 is turned off. The descent operation stops. Specifically, when the solenoid 40 is turned on, the main shaft 41 of the solenoid 40 pulls the link 42 upward against the coil spring 45 and rotates the link 43 clockwise, so that the claw 34 is rotated by the torsion spring 35. The ratchet 36 is engaged with the urging force. Regardless of whether or not the claw 34 is engaged with the ratchet 36, the claw 34 always swings at a predetermined angle together with the swing link 33 during rotation of the barrel. Therefore, when the pawl 34 is not engaged with the ratchet 36, that is, when the solenoid 40 is OFF, the pawl 34 slides on the outer surface of the link 43, so that the ratchet 36 does not rotate and remains stopped. In the ON state, the claw 34 meshes with the ratchet 36, so that the ratchet 36 intermittently rotates counterclockwise by a predetermined angle in accordance with the swinging motion of the claw 34. As the ratchet 36 rotates intermittently, the sprocket 26 also rotates intermittently, so that the paper discharge tray 1 is intermittently lowered by a predetermined amount, while the solenoid 40 remains in the ON state. The paper base 1 continues to descend.

The control unit 7 turns off the solenoid 40 after a predetermined connection time and stops the paper discharge table 1, but after the paper discharge table 1 starts to descend, that is, until the solenoid 40 is turned on. Control is performed to expand / contract the connection time per one time from when the power is turned off to when it is turned off according to the rotational speed of the body. An example of the control are shown in the flow chart in FIG. 2, the control unit 7, when the rotation speed of the barrel is greater than or equal to the reference speed and time have short connection time, is smaller than the reference speed rotation speed of the barrel It is to have the long time the connection time to the case. Specifically, since the control unit 7 controls ON / OFF of the solenoid 40, in order to shorten or increase the connection time, the ON time while the solenoid 40 is in the ON state is lengthened or shortened. Or That is, the rotation speed of the cylinder is compared with the reference speed (step 100). If the rotation speed is higher than the reference speed, the ON time is shortened (step 101). If the rotation speed is lower than the reference speed, the ON time is reduced. Increase the length (step 102). In addition, since the main body of the printing press always knows the rotation speed of the cylinder, the control unit 7 receives the input from the printer and determines the rotation speed and a reference speed that is preset and stored in a memory such as a ROM. Compare. The reference speed is, for example, a substantially central rotational speed in a range of rotational speeds usable in the printing press. If this reference speed can be set arbitrarily by inputting it from an input device such as a touch panel or keyboard, the operator can change the reference speed according to the printing conditions, the thickness of the sheet used, the printing environment, etc. it can.

  Furthermore, since the connection time only needs to be relatively shorter or longer than the other, the connection time when the rotation speed is higher than the reference speed or lower than the reference speed may not be constant. However, for example, when the rotation speed of the cylinder is equal to or higher than the reference speed, the first connection time is used. When the rotation speed of the cylinder is smaller than the reference speed, the second connection time is longer than the first connection time. Control is facilitated if the first and second connection times are fixed. That is, when the cylinder rotation speed is higher than the reference speed, the first ON time is set (step 101). When the cylinder rotation speed is lower than the reference speed, the second ON time is longer than the first ON time. (Step 102). The first ON time and the second ON time are stored in advance in a memory such as a ROM. However, the operator may change the setting so that the input can be made from various input devices as described above. .

  When the sensor 6 detects the uppermost paper 5 and the signal is sent to the control unit 7 (step 104), the control unit 7 turns on the solenoid 40 (step 105) to start the lowering operation of the paper discharge tray 1. . After the solenoid 40 is turned on, the control unit 7 counts the time with an internal timer and turns off the solenoid 40 when the ON time determined in steps 101 and 102 elapses (steps 106 and 107). Thus, the lowering operation of the paper discharge tray 1 in one connection time is completed, and this lowering operation is repeated intermittently until the end of printing (step 103).

  As described above, when the rotation speed of the cylinder is high, the amount of lowering of the paper discharge tray 1 per connection time can be reduced by shortening the ON time as compared with the prior art, and the sheet fall distance As a result, the paper alignment accuracy can be improved. In addition, when the cylinder rotation speed is low, the amount of lowering of the paper discharge tray 1 per connection time can be increased by increasing the ON time as compared with the conventional one, and the number of times the solenoid 40 is switched ON / OFF. The durability of the solenoid 40 can be improved.

  It should be noted that the connection time is gradually shortened according to the increase in the rotation speed of the cylinder, either when the cylinder rotation speed is higher than the reference speed or when the cylinder rotation speed is lower than the reference speed, or in both cases The connection time may be gradually shortened as the rotational speed of the cylinder increases. As a method of changing the connection time in accordance with the rotational speed of the cylinder, the connection time may be changed linearly in addition to changing the connection time in a stepwise manner. That is, the first ON time or the second ON time may be obtained by multiplying the rotation speed by the reference speed and multiplying by a predetermined proportional coefficient.

  In addition to the above-described control method for expanding / contracting the connection time per switching according to the rotation speed of the cylinder, for example, the increase in the rotation speed in the entire range of the rotation speed of the cylinder Accordingly, the connection time per switching unit 4 may be gradually shortened. That is, the ON time may be gradually shortened as the rotational speed increases, and the solenoid 40 may be turned OFF when the ON time has elapsed. Also in this case, as described above, the ON time can be shortened stepwise as the rotation speed increases, or the ON time can be obtained by multiplying the rotation speed by a predetermined proportional coefficient. In particular, if the ON time is controlled so that the amount of lowering of the paper discharge tray 1 per connection time is constant regardless of the rotation speed, variations in the falling distance of the sheet can be suppressed. The alignment accuracy is further increased, which is preferable.

  Although the control for extending / contracting the connection time from the start of the lowering of the discharge tray 1 to the stop in one connection according to the rotation speed of the cylinder has been described, the drive is performed in one operation of the solenoid 40. Control may be made to stop the paper discharge tray 1 when the number of rotations of the cylinder from the start of force transmission reaches the reference number. An example of this control is shown in the flowchart of FIG. When the sensor 6 detects the uppermost paper 5 and a signal is sent to the control unit 7 (step 201), the control unit 7 turns on the solenoid 40 to start the lowering operation of the paper discharge tray 1 (step 202). After the solenoid 40 is turned on, the control unit 7 starts counting the number of rotations of the cylinder (step 203). When the number of rotations reaches the reference number, the solenoid 40 is turned off (steps 204 and 205), and this lowering operation is repeated until the end of printing (step 200). In this way, by setting the number of rotations of the cylinder between the time when the solenoid 40 is turned on and the time when the solenoid 40 is turned off to a certain number, the amount of lowering of the paper discharge tray 1 in one connection is always set regardless of the rotation speed of the cylinder. It can be a certain amount. Therefore, when the cylinder rotation speed is high, the paper alignment accuracy of the paper discharge is improved as compared with the conventional case, and when the cylinder rotation speed is low, the durability of the solenoid 40 can be improved. Incidentally, since the rotation state of the cylinder is always detected in the main body of the printing press, the number of rotations of the cylinder can be easily counted by using the signal.

  In the above description, the switching unit 4 using the solenoid 40 has been described. However, the configuration of the switching unit 4 can be changed as appropriate, and the switching unit 4 can be used when the rotational speed of the cylinder is low in any configuration. Durability can be improved.

1 is a front view showing a sheet discharge device of a sheet-fed printing press according to an embodiment of the present invention. 6 is a flowchart illustrating an example of a control method of the paper discharge device. 6 is a flowchart illustrating an example of a control method of the paper discharge device.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Paper discharge stand, 2 ... Paper discharge stand drive part, 3 ... Driving force transmission part, 4 ... Switching part, 5 ... Top paper, 6 ... Sensor, 7 ... Control part

Claims (5)

A sheet discharge table on which sheets printed on the cylinder of the printing machine are sequentially stacked, a sheet discharge table driving unit that receives a driving force from a rotation driving unit of the cylinder of the printing machine, and lowers the sheet discharge table; Switching for selectively switching between a driving force transmission unit that transmits a driving force from the driving unit to the paper discharge table driving unit, and a connection state in which the driving force is transmitted and a blocking state in which the driving force is blocked. Each time the uppermost sheet on the sheet discharge table reaches a predetermined height, the switching unit is connected to the driving force transmission unit and the sheet discharge table is lowered. For a sheet-fed printing machine paper discharge machine where the paper delivery stand stops with the transmission part shut off, the connection time per switching part is the first connection when the cylinder rotation speed is higher than the reference speed. Time, and if the rotation speed of the cylinder is lower than the reference speed, Long second connection time a paper discharge device of the sheet-fed printing press, characterized by than. The connection time is gradually shortened according to an increase in the rotational speed of the cylinder in at least one of a case where the rotational speed of the cylinder is equal to or higher than the reference speed and a case where the rotational speed of the cylinder is smaller than the reference speed. Paper sheet printer. A sheet discharge table on which sheets printed on the cylinder of the printing machine are sequentially stacked, a sheet discharge table driving unit that receives a driving force from a rotation driving unit of the cylinder of the printing machine, and lowers the sheet discharge table; Switching for selectively switching between a driving force transmission unit that transmits a driving force from the driving unit to the paper discharge table driving unit, and a connection state in which the driving force is transmitted and a blocking state in which the driving force is blocked. Each time the uppermost sheet on the sheet discharge table reaches a predetermined height, the switching unit is connected to the driving force transmission unit and the sheet discharge table is lowered. In the sheet discharge device of the sheet-fed printing press where the sheet discharge stand stops with the transmission unit shut off, the connection time per switching unit is gradually shortened according to an increase in the rotation speed of the cylinder. A paper discharge device for sheet-fed printing machines. 4. The sheet discharge device for a sheet-fed printing press according to claim 3 , wherein the connection time is increased or decreased in accordance with the rotation speed of the cylinder so that the descending amount by which the sheet discharge table is lowered during one connection time is constant . A sheet discharge table on which sheets printed on the cylinder of the printing machine are sequentially stacked, a sheet discharge table driving unit that receives a driving force from a rotation driving unit of the cylinder of the printing machine, and lowers the sheet discharge table; Switching for selectively switching between a driving force transmission unit that transmits a driving force from the driving unit to the paper discharge table driving unit, and a connection state in which the driving force is transmitted and a blocking state in which the driving force is blocked. Each time the uppermost sheet on the paper discharge tray reaches a predetermined height, the switching unit lowers the paper discharge table with the driving force transmission unit connected and the switching unit shuts off the driving force transmission unit. In the paper discharge device of the sheet-fed printing press where the paper discharge stand stops, the switching unit is driven when the number of rotations of the cylinder from the start of driving force transmission reaches the reference number every time the driving force transmission unit is connected. A sheet discharge device for a sheet-fed printing machine, wherein the force transmission unit is cut off .

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