JP2002060104A - Web tension control method and device for rotary press - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a web tension control method that can control web tension to desired tension with high accuracy even during the acceleration of a printer, coping with the sudden fluctuation of web tension. SOLUTION: In this web tension control method for a rotary press controlling the tension of the web 4, which is to be fed to a printing part 11, positioned upstream of the printing part to compensate the web tension on the paper discharge side of the printing part, the target value of web feed speed on the feed side of the printing part is preset to start the conveyance of the web, and the web feed speed is controlled on the basis of the web tension value while measuring the present web tension value on the feed side of the printing part. The web tension value after printing on the discharge side of the printing part is suitably measured, and the target value is corrected on the basis of the web tension value after printing to compensate the web tension value after printing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a web tension control for a rotary printing press which feeds a web to a printing section, controls the web tension on the upstream side of the printing section, and compensates for the web tension on the paper ejection side of the printing section. Method and apparatus.

[0002]

2. Description of the Related Art Conventionally, a web tension control device of a rotary printing press that controls the tension of a web fed to a printing unit and controls the web tension on the paper feeding side of the printing unit and compensates the web tension on the discharge side of the printing unit. The web is fed to the printing unit via a dancer roller disposed on the printing unit paper feed side, the web tension is controlled by detecting the position of the dancer roller, and the tension disposed on the printing unit discharge side. The detector detects the web tension on the print section discharge side as appropriate, and corrects the web tension on the print section feed side by operator operation to compensate for the web tension on the print section discharge side.

FIG. 5 shows an example of such a prior art web tension control system with dancer rollers. In FIG. 5, the control of the tension applied to the wrapping paper will be described first. The tension of the web 4 is detected by a tension detector 27, and the signal is input to a paper feed unit tension controller 28. The paper feeding unit tension controller 28 compares a preset tension signal value with a tension signal value from the tension detector 27, and if there is a deviation between the two, a correction signal corresponding to the deviation is supplied to the brake of the paper feeding device. Input to the control device 29. Paper feeder brake controller 2
In step 9, the correction signal is converted into a control signal to operate the brake 26 of the sheet feeding device. With this control, the web tension in the paper feeding unit is kept constant.

Next, control of web tension in the infeed section 38 for controlling the transport of the web 4 to the printing unit 11 will be described. In the infeed section 38, a dancer roller 30 is provided to absorb a sudden change in the tension of the web 4. The dancer roller 30 is shown in FIG.
, The upward force T1 + T due to the tension of the web 4
2 and a force F obtained by applying a downward force of the air pressurizer 31 to its own gravity is balanced so as to be stationary.

If the tension of the web 4 fluctuates temporarily for some reason, the balance of the force is lost, and the fluctuation of the position of the dancer roller 30 absorbs the rapid fluctuation of the tension. That is, when the tension of the web 4 is to be increased, the position of the dancer roller 30 is raised to absorb the increased tension. Conversely, when the tension of the web 4 is about to decrease, the position of the dancer roller 30 is lowered to absorb the decrease in tension. In this way, the tension of the web 4 is kept constant. In this case, if the position of the dancer roller 30 deviates from the center position and reaches the stroke limit of the vertical movement, it is impossible to cope with the next fluctuation. Therefore, the vertical position of the dancer roller 30 is detected by the dancer roller position detector 32, and the dancer roller 30 is detected.
Is controlled to be always at the center position.

Next, this control, that is, in-feed tension control will be described. First, the dancer roller position detector 32 detects the vertical position of the dancer roller 30,
This signal is input to the in-feed tension controller 33. In the infeed tension controller 33, a control signal corresponding to the amount by which the dancer roller 30 deviates from the center position is input to the motor driver. The motor driver 34 sends a drive signal to a motor 35 and an in-feed roller 36
Adjust the rotation speed of the.

When the rotational speed of the infeed roller 36 changes in the correction direction, the position of the dancer roller 30 moves slowly toward the center position. When the dancer roller 30 returns to the center position, the rotation speed of the in-feed tension roller 36 maintains that speed.

Next, an indication of the outlet tension, that is, the printing unit 1
The display of the tension of the web 4 coming out of 1 will be described.
The web 4 coming out of the printing unit 11 is a tension detector 1
2 through a plurality of drag rollers 17
Enter 3. The tension signal of the web 4 detected by the tension detector 12 is input to the printing unit outlet tension display device 37 to display the tension value.

The operator makes a decision to change the web tension target value of the infeed section 38 based on the displayed tension value. If the value displayed on the printing unit outlet tension display device 37 is not an appropriate value corresponding to the paper width of the web 4 and the number of printing colors, etc., and the operator wants to raise (lower) more, the operator needs to adjust the tension value of the infeed section 38. Perform the operation to raise (lower). That is, the operator increases (decreases) the air pressure supplied to the air pressurizer 31 pressing the dancer roller 30 of the infeed section 38. Then, the dancer roller 30, which has been maintaining the horizontal position, starts to descend (ascend) with the force of the air pressure.

The in-feed tension controller 33 controls the dancer roller 30 to keep it in a horizontal position.
Increase (fall) the web tension, and then
Correct 0 to the horizontal state and stabilize. Therefore, the target value of the web tension of the in-feed unit 38 rises (falls) to a value at which the operator operates the air pressure.

[0011]

In this conventional system,
There were the following problems. 1) When the printing press accelerates, the web 4 accelerates the guide rollers and the like around which the web 4 is wound, so the tension increases. However, there are a plurality of rollers from the dancer roller 30 to the printing point where printing is performed. In addition, the correction of the tension fluctuation from the dancer roller 30, which is the detection point of the tension fluctuation, to the printing point cannot be performed. 2) With the air pressure of the air pressurizer 31, the dancer roller 30
Is adjusted and the position of the dancer roller 30 is detected and adjusted by the dancer roller position detector 32.
The set value of the web 4 tension cannot be directly grasped. Therefore,
It is difficult to set the target value of the tension with high accuracy or to continuously change the target value. 3) According to the value of the printing unit outlet tension display device 37,
It is necessary for the operator to determine the appropriate set value of the infeed tension and manually change the dancer roller air pressure of the infeed portion 38. 4) When determining an appropriate initial value for the infeed tension, printing individual data such as an ink clutch ON signal, data on a web 4 paper width and the number of colors to be printed based on a reel arm position signal, and the like. The data of the machine's ready state must also be set taking parameters into account.

It is an object of the present invention to provide a web tension control method and apparatus which can cope with a sudden change in web tension and can accurately control a desired web tension even during printing machine acceleration. Another object of the present invention is to automatically set a target value for tension control of an in-feed unit based on data on a preparation state of a printing press, start printing, and make sure that a printing unit outlet tension is appropriate during main printing. It is an object of the present invention to provide a web tension control method and apparatus for automatically controlling the target value of the in-feed portion tension control so as to correct the target value so as to obtain a desired value.

[0013]

A first aspect of the present invention is an invention of a control method, which controls the tension of a web fed to a printing section and fed to a printing section, and controls the web tension on the printing section ejection side. In a web tension control method of a rotary printing press that compensates for web tension, a target value of a web feeding speed of a printing unit feeding side is set in advance, and web transport is started, and a current web tension of a printing unit feeding side is set. The web feed speed is controlled based on the web tension value while measuring the web tension value, and at the appropriate time, the web tension value after printing on the printing section discharge side is measured, and the target web tension value is determined based on the web tension value after printing. Correcting the web tension value after printing.

According to a fifth aspect of the present invention, there is provided an apparatus for carrying out the first aspect of the present invention, wherein the tension of a web on a printing section feeding side, which is fed to a printing section, is controlled. A web tension control device for a rotary printing press for compensating for a web tension on a paper discharge side of the printing unit; a web tension target value setting unit for setting a target value of a web tension on a paper feeding side of the printing unit; Feed speed control system for controlling the feed speed of the web on the printing side, a first tension detector interposed in the feed speed control system for measuring the tension of the web on the feed side of the printing unit, and the first tension A web feed speed control means for controlling a rotation speed of a motor for transporting the web based on a target value set by the web tension target value setting means using output data of a detector; and A second tension that is placed and measures the web tension value after printing A web tension target value correcting means for comparing a detection value of the second tension detector with a target value of the web tension on the printing unit paper feed side in advance and outputting a deviation thereof; Set the target value of the web feed speed on the paper feed side, start web transport, and control the web feed speed based on the web tension value while measuring the current web tension value on the print unit paper feed side. And at the appropriate time, measure a web tension value after printing on the printing unit discharge side, correct the target value based on the web tension value after printing, and compensate the web tension value after printing. And

In this invention, the printing unit paper feed is performed in advance based on print preparation data such as data of the printing press, such as an ink clutch engagement signal, and data of the paper width of the web 4 and the number of colors to be printed based on the reel arm position signal. Since the web transport is started by setting the target value of the web feeding speed of the printing side, the web feeding speed is controlled based on the web tension value while measuring the web tension value of the current printing unit paper feeding side. , Automatically sets the target value of web tension control based on the data of the preparation state of the printing press, starts printing, can respond to sudden fluctuations in tension, accurately during printing press acceleration, with the desired web tension. Can be controlled.

Then, the web tension value after printing on the printing unit discharge side is measured as appropriate, and the target value is corrected based on the web tension value after printing. It can be automatically compensated for the value and does not need to be set manually by the operator.

The present invention is also effective in that the control of the web paper feeding speed on the paper feeding side of the printing unit is such that the rotation speed of a drive motor directly connected to an infeed roller for transporting the web is controlled. It is. According to this technical means, since the drive motor directly connected to the infeed roller is used, a tension control system having excellent responsiveness in which the rotational speed follows the sudden change in the tension of the web 4 can be constructed. In other words, since the speed of the motor 2 is controlled, the motor 2 produces a speed deviation in the direction in which the tension is loosened in response to an instantaneous tension change, for example, a sudden increase in the tension. Become. Conversely, in the case of a sudden drop in tension, the same applies in the opposite direction.

It is also an effective means of the present invention that the web feed speed on the print unit feed side is controlled stepwise. According to such technical means, FIG.
4B, the overshoot OS1 increases as shown by the broken line in FIG.
2 is small, and more stable tension can be obtained.

It is also an effective means of the present invention that the control of the web feeding speed on the printing unit feeding side is performed by proportional control. According to such technical means, FIG.
4A, the overshoot OS3 is smaller than that shown in FIG. 4C, and smaller than the OS2 shown in FIG. 4B. There is an effect that a stable tension can be obtained.

It is also an effective means of the present invention that the apparatus further comprises a data acquisition control means for controlling the acquisition of the detection data from the second tension detector to the web tension target value correction means. .

According to this technical means, the data acquisition control means can acquire the correction data at a predetermined correction data sending time interval and the correction data sending time, and average the current data. The tension at the outlet side of the printing unit fluctuates due to the tension of the infeed unit, but its influence response has a large time delay, so it is necessary to correct the infeed tension data at a sufficient time interval or at a sufficiently low correction speed. However, the data sending time interval and the corrected data sending time can be set according to various specifications by such technical means.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be illustratively described in detail below with reference to the drawings. However, dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, and are merely illustrative examples. It's just

FIG. 1 is a configuration diagram of a dancer rollerless web tension control system according to a first embodiment of the present invention. FIG. 2 is a control block diagram of the web tension control system in the infeed section according to the first embodiment of the present invention, and FIG. 3 is a setting factor diagram of the infeed tension according to the first embodiment of the present invention. .

In FIG. 1, the difference from the conventional structure is that the tension detector 10 is provided as short as possible to the printing unit by eliminating the dancer roller 30 in the infeed section 8.
, The state of the web tension is detected, the drive of the infeed roller 1 is driven by a motor, and the target value of the web feed speed for controlling the infeed tension is automatically set.

In FIG. 1, a web 4 conveyed from a paper feeding unit passes through a roller 5 via an in-feed roller 1 and a fixed roller 9 driven by a motor 2, and is sent to a printing unit 11. Tension detector 10 coupled to roller 5
The load cell type load detector (for example, a load cell type load detector) is configured to input a signal proportional to the tension of the web 4 to the PI control device of the motor driver 3.

On the other hand, the PI controller receives a target value of the driving speed of the motor 2 from the master controller 7.
The web tension signal detected by the tension detector 10 enters the motor driver 3 and is constantly compared with a target tension signal set in advance in the master controller 7 and sent to the motor driver 3. When a deviation occurs, the speed of the motor 2 is corrected. The PI control device includes a tension controller 20 including a PI controller 18 and an upper and lower limit processing unit 19 as shown in FIG.

The function of the control system of the tension control unit 20 will be described with reference to FIGS. 1 and 2. First, the target tension command from the master controller 7 and the tension detector 10 will be described.
From the current tension value, and the deviation is compared with the tension control unit 2
0 is input to the PI controller 18. Based on this deviation signal, the PI controller 18 transfers the transfer function G (s) = Kp {1+ (1 / K) of the PI controller 18 when Kp is a proportional gain and K1 is a previous proportional element.
1s)}, and outputs it as a speed fine adjustment value (%). The speed fine adjustment control of the motor 2 is performed through the upper / lower limit processing unit 19 of the fine adjustment value (%). The limit processing is configured so as not to cause a paper break or the like due to an excessive correction operation.

The speed fine adjustment value (%) is input to a motor 2 for driving the infeed roller 1 via a motor driver, and the rotation speed of the infeed roller 1 is changed by an amount corresponding to the input signal. The speed changes according to the fine adjustment value (%), and the tension of the web 4 changes according to the speed relative to the speed of the printing unit. Incidentally, the current tension value is actually controlled by detecting the value taking into account the spring constant of the web 4 and the first-order lag element by the noise filter included in the amplifier or driver for the tension detector as the current value of the web tension. It is configured as follows. A time delay element T1 may be used instead of K1.

Next, the automatic setting of the target value of the web feed speed for the in-feed tension control will be described. The relationship between the infeed section tension (tension on the print section paper feed side) and the print exit tension (tension on the print section discharge side)
As shown in FIG. 3, there is basically a proportional relationship (of course, the proportional coefficient changes depending on the paper quality and the like). The optimum value of the printing outlet tension is determined by the width of the web 4 (A winding, C winding, D winding, etc.). By utilizing this, the tension target value of in-feed is automatically set before printing. That is, the width of the web 4 is determined by a signal (not shown) of a reel arm on which the take-up paper of the sheet feeding device is mounted, the number of printing colors is determined by a signal of an ink clutch of each printing device (signal with an inking device), Judge from input data such as paper brand used.

As shown in FIG. 1, a reel arm position signal, a signal for entering an inking device, paper quality data, and the like are taken into a tension calculating device 14 for setting an initial tension target value. The value is transmitted to the sequencer 6 and further transmitted to the master controller 7,
The target value of the tension controller 20 of the motor driver 3 (FIG. 4)
(Shown in (c)).

As described above, the target value of the web tension control can be given in advance by the state signal of the printing press before the start of printing. Then, the tension of the current value of the running EUB 4 is detected by the tension detector 10, the result is returned to the motor driver 3, the difference from the target value is calculated, and automatic control is performed so as to correct the difference.

Next, a method for automatically correcting the target value will be described. In the present embodiment, the operation is performed with the tension target value set before printing, and after a suitable time, the target value data sent to the master controller 7 is corrected so that the target value of the infeed tension is corrected by the tension at the printing unit outlet. Circuit.

That is, the sequencer 6 is provided with a changeover switch 21. After the target value data is sent to the master controller 7, the switch 21 is switched to the broken line side to change the tension (tension detector) after the printing unit 11. The target value of the in-feed tension control is corrected so that the value (12) becomes a desired value.

The current tension value at the printing unit outlet is measured by the tension detector 12 and transmitted to the sequencer 6. The sequencer 6 compares a print exit tension optimum value determined before printing with the current exit tension value, and calculates a difference between them.
2 are provided. The comparison operation unit 22 compares the print outlet tension optimum value with the current outlet tension value, and adjusts the in-feed target tension value sent to the master controller 7 by a value corresponding to the difference. In this way, the set in-feed tension target value is corrected by a value corresponding to the difference between the desired tension value at the printing outlet and the current tension value.

The sequencer 6 is provided with a data fetch control unit 23. The tension at the outlet of the printing unit 11 fluctuates due to the tension of the infeed portion. However, since the influence response has a large time delay, it is necessary to correct the infeed tension data at a sufficient time interval or at a sufficiently low correction speed. is there. Therefore, the data capture control unit 23 captures the correction data at a predetermined correction data transmission time interval and correction data transmission time, averages the current data, compares the averaged data with the initial target value by the comparison operation circuit 22, and compares the averaged data with the initial target value. The initial target value is corrected by a value corresponding to the difference.

As described above, according to the present embodiment,
It can cope with sudden fluctuations in tension.
The web tension can be controlled to a desired value, and the target value of the tension control of the infeed unit 8 is automatically set based on the data of the preparation state of the printing press, and printing is started. It is possible to automatically correct the target value of the in-feed portion tension control so as to have an appropriate value.

Further, in this embodiment, since the drive motor directly connected to the in-feed roller is used, a tension control system having excellent responsiveness in which the rotation speed follows the sudden change in the tension of the web 4 is employed. Is building. Since the speed of the motor 2 is controlled, the motor 2 generates a speed deviation in the direction in which the tension is loosened in response to an instantaneous tension change, for example, a sudden rise in the tension, and the motor 2 performs control immediately corresponding to the change, thus providing a cushion-like effect. Conversely, in the case of a sudden drop in tension, the same applies in the opposite direction.

In addition to being able to cope with sudden fluctuations in tension, a tension detector 10 is provided so as to detect the tension at a portion near the printing point on the paper feed side of the printing unit whose tension is to be controlled. Even when the tension fluctuation is likely to occur, controlling the tension of the most necessary portion has the effect of ensuring stable printing quality.

Further, there is no need for a large installation space unlike the dancer roller 30, so that the entire installation space can be reduced, and the equipment can be simplified and the cost can be reduced.

As described above, the target value of the in-feed portion tension control is set at the start of printing according to the position signal of the reel arm, the signal for engaging the ink clutch, the input signal such as paper quality, and the like. And the number of colors to be printed is determined, the control target value is automatically set, and the operation is started. After an appropriate time has elapsed, the target value of the in-feed tension control is corrected by the tension value at the outlet of the printing unit 11 (the value of the detector 12).

In the normal printing operation, color adjustment and registration are performed at a medium speed after the start, and the main printing is started at a high speed if it is improved.
In order to stabilize the web tension at the printing point of the printing unit 11, it seems good to start printing with the tension value at the printing outlet as a control target, but printing is not performed initially, and one-color printing is not performed. Each time the web tension decreases. The amount of this tension drop varies depending on the dampening solution applied based on the amount of the picture, or the material and brand of the web 4, and the tension at the printing outlet delays the response to the change in the in-feed tension. It is not appropriate to control the tension of the infeed section 8 using the web tension at the printing outlet as the current tension value.
Therefore, the infeed tension control starts printing at the initially set infeed target value, and after an appropriate time, uses the printing unit outlet tension to correct the infeed tension. That is, the target value of the infeed tension is corrected. As a result, the tension of the infeed section 8 is always controlled to the target value, and the control is performed to correct the target value at a certain time.

When correcting the tension target value of the infeed section 8 by the tension at the outlet of the printing unit 11, the correction is performed in sufficient time so as not to cause hunting, not in real time. This allows
While the tension of the in-feed unit 8 is always controlled to be constant, the tension after printing is sometimes corrected so as to become a target value, and the final color unit of the printing unit 11 is also printed with the appropriate tension, and as a whole, appropriate printing is performed. There is an effect that the state can be maintained.

This eliminates the need for the operator to pay attention to the tension at the printing outlet from time to time and corrects the target value of the infeed tension, eliminates oversight, etc., saves labor, achieves stable printing, and improves reliability. improves.

FIG. 4C is an explanatory diagram of a method of assigning the initial tension target value according to the first embodiment. Transfer function G (s) of PI controller 18 = Kp {1+ (1 / K1s)}
4A, the target value of the web tension control of the in-feed unit 8 determined before printing is applied in a manner that 100% of the target value is applied from the beginning as shown in FIG. In the first embodiment, as shown in FIG. 4C, the values are continuously provided so that the target value becomes 100% after a specific time.

FIG. 4A shows a second embodiment.
The target value is set to 100 from the beginning instead of the I controller section 18.
A transfer function given% is prepared so that a web feeding speed corresponding to a web tension of a predetermined target value can be reached after a predetermined time. As shown by the broken line, the target value has reached the predetermined target value after the overshoot OS1 and the undershoot.

FIG. 4B shows a third embodiment.
In the configuration of the embodiment, the method of giving the target value of the web tension control of the infeed unit 8 determined before printing is such that 100% of the target value is given from the beginning as shown in FIG. On the other hand, in the present embodiment, the target value is provided in a plurality of times. In this embodiment, the first
In the embodiment, the overshoot OS1 and the undershoot are reduced as shown in FIG. 4B, while the overshoot OS1 is increased as shown by the broken line in FIG. The stabilization to the target value is quick in time, and there is an effect that a more stable tension can be obtained.

As described in detail above, since the first embodiment has the PI controller 18, the overshoot and undershoot are smaller than those of the second and third embodiments, and the target is set. There is an effect that the web tension value is quickly reached in time and a more stable tension can be obtained.

[0048]

As described above in detail, according to the present invention, a target value of the web feeding speed of the printing unit paper feeding side is set in advance based on the print preparation data, the web transport is started, and the current printing unit feeding is started. Since the web feed speed is controlled based on the web tension value while measuring the web tension value on the paper side, the target value of the web tension control is automatically set based on the data of the ready state of the printing press, and the printing is performed. Can be started to cope with sudden fluctuations in tension, and the web tension can be controlled to a desired level with high accuracy even during press acceleration.

Further, the web tension value after printing on the paper discharge side of the printing unit is measured as appropriate, and the target value is corrected based on the web tension value after printing. It can be automatically compensated for the value and does not need to be set manually by the operator.

Further, by controlling the web feeding speed on the printing section feeding side in a stepwise manner, the overshoot with respect to the target value is reduced, and a stable tension can be obtained.

Further, by controlling the web feeding speed on the printing section feeding side by proportional control, overshoot with respect to the target value can be further reduced, and more stable tension can be obtained.

Further, the control of the web feeding speed on the printing section feeding side is performed by controlling the rotation speed of a drive motor directly connected to an infeed roller for feeding the web, thereby coping with a sudden change in the tension of the web 4. Thus, a tension control system excellent in responsiveness in which the rotation speed follows can be constructed.

Further, by including data acquisition control means for controlling the acquisition of the detection data from the second tension detector to the web tension target value correction means, various data acquisition control means can be used. The data sending time interval and the corrected data sending time can be set appropriately according to the specification. And so on.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a dancer rollerless web tension control system according to a first embodiment of the present invention.

FIG. 2 is a control block diagram of a web tension control system in the infeed section according to the first embodiment of the present invention.

FIG. 3 is a set factor diagram of an infeed tension according to the first embodiment of the present invention.

FIG. 4 is an explanatory diagram illustrating a method of controlling an in-feed tension to a target value according to the embodiment of the present invention.

FIG. 5 is a configuration diagram of a conventional web tension control system with dancer rollers.

6 is an operation explanatory diagram of FIG. 5;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 infeed roller 2 motor 3 motor driver 4 web 6 sequencer 7 master controller 8 infeed section, 10, 12 tension detector 11 printing unit (printing section) 14 tension calculator, 18 PI controller section 19 upper / lower limit processing section 20 Tension control unit 21 Switch, 22 Comparison operation unit 23 Capture control unit

Claims (9)

[Claims] 1. A web tension control method for a rotary printing press, wherein a web tension on a paper feeding side of a printing unit, which is fed to a printing unit, is controlled to compensate for a web tension on a paper discharging side of the printing unit. Set the target value of the web feed speed of the paper feed side, start the web conveyance, measure the current web tension value of the paper feed side of the printing unit, and set the web feed speed based on the web tension value. Control, and measure the web tension value after printing on the paper output side of the printing unit as appropriate.
Correcting the target value based on the web tension value after printing,
A web tension control method for a rotary printing press, wherein the web tension value after printing is compensated. 2. A web feeding speed of the printing unit feeding side,
2. The method according to claim 1, wherein the web tension is controlled stepwise. 3. The web tension control method for a rotary printing press according to claim 1, wherein the control of the web feeding speed on the printing unit paper feeding side is performed by proportional control. 4. The method according to claim 1, wherein the control of the web paper feeding speed on the paper feeding side of the printing unit is performed by controlling the rotation speed of a drive motor directly connected to an infeed roller for transporting the web. 4. The web tension control method for a rotary printing press according to 2 or 3. 5. A web tension control device for a rotary printing press, wherein the web tension is controlled by controlling a web tension on a paper feeding side of the printing unit to be fed to a printing unit and compensating for a web tension on the paper discharging side of the printing unit. A web tension target value setting means for setting a target value of the web tension on the paper feeding side; a paper feeding speed control system for controlling a web feeding speed of the web on the printing unit paper feeding side; A first tension detector for measuring the tension of the web on the paper feed side of the printing section; and a web based on a target value set by the web tension target value setting means using output data of the first tension detector. Web feed speed control means for controlling the rotation speed of a motor for transporting the paper; a second tension detector arranged on the paper ejection side of the printing unit for measuring a web tension value after printing; and a second tension detector. And the target web tension of the printing unit And a web tension target value correcting means for outputting a deviation of the target value. The target value of the web feeding speed of the printing unit feeding side is set in advance to start the web conveyance, and the current printing unit feeding While controlling the web tension value based on the web tension value while measuring the web tension value on the paper side, the web tension value after printing on the printing unit discharge side is measured as appropriate,
Correcting the target value based on the web tension value after printing,
A web tension controller for a rotary printing press, wherein the web tension value after printing is compensated. 6. A control unit for controlling a web feeding speed of the printing unit on a paper feeding side by controlling a rotation speed of the motor directly connected to an in-feed roller for transporting a web. A web tension control device for a rotary printing press as described in the above. 7. A web feeding speed of the printing unit feeding side,
7. The web tension control device for a rotary printing press according to claim 5, wherein control means for performing stepwise control is provided in a drive circuit of the motor. 8. The rotary printing press according to claim 5, wherein the control of the web feeding speed on the feeding side of the printing section is performed by providing a proportional control means in a drive circuit of the motor. Web tension control device. 9. The rotary printing press according to claim 5, further comprising data capture control means for controlling capture of detection data from said second tension detector to said web tension target value correction means. Web tension control device.