Method for controlling an apparatus for controlling a cutting position of a web member and device therefor

A control method for controlling a cut-off control apparatus in a printing press comprises a step of detecting an unstable factor such as a revolution number of a cylinder/a tensile value of a web in a printing press, a step for setting a stable factor such as a revolution number/a tensile value in an actual printing operation, and a control step for controlling the cut-off-control apparatus by comparing the detected unstable factor and the previously set stable factor to control a cutting position of a web in the printing press.

The entire disclosure of Japanese Patent Application No.2002-063073 filed on Mar. 8, 2002 including specification, claims, drawings and summary is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for controlling an apparatus for controlling a cutting position of a web member in a web cutting unit and a device therefor.

2. Prior Art

A conventional web rotary printing press is shown inFIGS. 8A,8B and8C.

In the drawings, a web member1is firstly folded along a centerline in a longitudinal direction and then cut. Each cut web piece is folded along a centerline in a transverse direction.

As shown inFIG. 8AthroughFIG. 8C, a web member1is printed by a printing unit in a rotary printing press, dried, and then cut and folded by a folding unit.

The web member1is fed from a compensation roller3to a drag roller4by a guide roller2. The web member1is folded along a centerline in a longitudinal direction by a triangle former5located in a downstream side. The folded web member1is fed to a cutting cylinder8through a lead roller6and a nipping roller7.

The web member1is cut and folded in a centerline along a transverse direction after passing the cutting cylinder8and the folding cylinder9before passing a gripping cylinder10. Then, each piece of cut web member1is discharged from a conveyor11.

On the web member1, the same printing image such as a picture pattern12is continuously printed. The web member1should be correctly cut along a boarder line between the both adjacent picture patterns2.

However, due to some unstable factors, for example, physically unevenness of the web member1and a rotational unbalance and variable load of mechanical parts, control accuracy of a cutting position is reduced.

In order to improve the control accuracy of the cutting position, various devices for controlling a cutting position, so called as cut-off-control devices, have been developed.

As one of the devices for controlling a cutting position, it has been known a device for controlling a cutting position by adjusting a compensating roller3forwardly/rewardly in accordance with a difference between a pulse signal generated with respect to each cutting length by a cutting reference signal generator13mounted on the cutting cylinder8and a signal generated by a detecting head14positioned at an upper portion of the drag roller4for detecting each picture pattern12.

In an above described control device for controlling an apparatus for controlling a cutting position in a web rotary printing press, the control device is switched on/off simultaneously with a cylinder in the printing press is attached/detached. In such a moment, tensile force of the web member1is varying so that a position of the compensating roller3is displaced from an original printing position. Therefore, in order to print picture patterns on a web again, cutting is not operated at a correct position until the compensating roller3is returned to the original printing position. It has to wait for a time and waste a large amount of printing materials.

For example, as shown inFIGS. 7A,7B and7C, the smaller the rotational speed of the printing press (revolution number per unit time) becomes, the smaller a tensile value of the web member1becomes. The larger the rotational speed of the printing press becomes, the larger the tensile value of the web member1becomes. When the rotational speed of the printing press becomes constant, the tensile value becomes stable. However, the cylinder of the printing press is pulled out and pushed back in the case when the rotational speed of the printing press is at the predetermined speed. If the apparatus for controlling a cutting position is switched on during an interval between the cylinder being rotated at a constant speed and the cylinder of the printing press being pulled out, and during an interval between the cylinder of the printing press being pushed back and the cylinder being rotated at a constant speed, a position of the compensating roller3is largely displaced due to varying tensile value of the web member1. In the case where the printing press is intermitted and restarted, the position of the compensating roller3can not be quickly returned to a position where the cylinder of the printing press can be rotated at the constant speed. Thus, a large amount of printing material such as pieces of web incorrectly cut is wasted.

Therefore, the position of the compensating roller3is manually adjusted in an interval as shown in a bi-directional arrow inFIG. 7Aso as to cut the web member1quickly on a correct boarder line.

A purpose of the present invention is to resolve the above drawbacks and to provide a control device for controlling an apparatus for controlling a cutting position of a web cutting unit in a printing press wherein the control device is switched ON/OFF in accordance with the rotational speed of the printing press or the tensile force of the web in an actual printing operation.

SUMMARY OF THE INVENTION

To resolve the above subject, a method for controlling an apparatus for controlling a cutting position of a web member of a web cutting unit according to the present invention detects unstable factors such as a revolution of a cylinder and a tensile value of a web member in a printing press.

In the case where the unstable factor is a revolution number of a printing cylinder, a method according to the present invention comprises a revolution number detecting step for detecting revolution number of a printing press, a revolution number setting step for setting a revolution number in an actual printing operation, and a control step for controlling the apparatus for controlling a cutting position of a web member in accordance with signals output in the revolution number detecting step and the revolution number setting step.

The method further comprises a step for starting a control of the apparatus for controlling a cutting position of a web member in the case where a present revolution number detected in the revolution number detecting step is larger than a number which is the set revolution number read out from the revolution number setting step multiplied by a predetermined ratio (for example 95%), and a step for stopping a control of the apparatus for controlling a cutting position of a web member in the case where a present revolution number detected in the revolution number detecting step is less than a number which is the set revolution number read out from the revolution number setting step multiplied by a predetermined ratio.

In the case where the unstable factor is a tensile value of a web member, a method according to the present invention comprises a tensile force detecting step for detecting a tensile value of a web member, and a control step for controlling the device for controlling a cutting position of a web member in accordance with a signal output in the tensile force detecting step.

The method further comprises a step for starting a control of the apparatus for controlling a cutting position of a web member in the case where a difference between a present tensile value of a web member detected in the tensile detecting step and the reference tensile value is less an allowable range and a step for stopping a control of the apparatus for controlling a cutting position of a web member in the case where a difference between a present tensile value of a web member detected in the tensile detecting step and the reference tensile value is larger an allowable value.

To resolve the above subject, a control device for controlling an apparatus for controlling a cutting position of a web member of a web cutting unit in a printing press comprises an unstable factor detecting means, a stable factor setting means, and control means for controlling a cutting position in a web member in accordance with signals from the unstable factor detecting means and the stable factor setting means.

In the case where the unstable factor is a revolution number, the device according to the present invention comprises revolution number detecting means for detecting a revolution number of a printing press, revolution number setting means for setting a revolution number of the printing press in an actual printing operation, and control means for controlling a cutting position in a web member in accordance with signals output from the revolution number detecting means and the revolution number setting means.

In the case where the unstable factor is a tensile value of a web member, the device according to the present invention comprises tensile detecting means for detecting a tensile value of a web member and control means for controlling an apparatus for controlling a cutting position of a cutting unit, in accordance with a signal from the tensile detecting means.

The device may comprise a compensating roller movably supported so as to vary a transport length of a web member and adjust a cutting position of the web member, detecting means for detecting a mark printed on the web member, and control means for moving a position of the compensating roller in accordance with a signal output from the detecting means.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the present invention, a control device, equipped at an apparatus for controlling a cutting position of a cutting unit in a printing press, is switched ON/OFF in accordance with a condition whether a revolution number of a printing press is different from a revolution number of the printing press in an actual printing operation or tensile force of a printing press such as a tensile force with respect to a web member is stable.

The present invention will be explained with reference to accompanying drawings.

FIG. 1shows the first embodiment of a control device for controlling a web member cutting position in a web member cutting device according to the present invention.

As shown inFIG. 1, a control device100is connected to a cut-off-control device200through I/F101and201.

The control device100comprises a CPU102, an I/O103, an input device104, a display device105and an output device106, wherein the input device104, a display device105and the output device106is connected to the CPU102through the I/O103, respectively.

The control device100further comprises ROM107, RAM108, memory means109for memorizing a revolution number of a printing press in the case of switching on/off the cut-off-control device, a memory120for memorizing a set revolution number in an actual printing operation of the printing press(set by a revolution number setting device122) and memory121for memorizing a present revolution number of the printing press.

The memory means109for memorizing/outputting a revolution number records a revolution number of a printing press in the case where the cutoff-control switch is switched on/off.

The control device100is connected to a rotary encoder112for a printing press driving motor through I/O110and F/V111and connected to a control device114of a printing press through I/F113.

A device for setting a set revolution number in an actual printing operation of the printing press is connected to the control device114of the printing press.

On the other hand, the cut-off-control device200comprises CPU202, ROM203, RAM204, an I/O205and a register mark detector206wherein the register mark detector206is connected to the CPU202through the I/O205.

The register mark detector206determines a cutting position by detecting a register mark wherein the register mark is marked in an outside of the picture pattern.

The cut-off-control device200is connected to a compensating roller motor209through I/O207and a compensating roller motor driver208and connected to a rotary encoder211through a counter210.

The compensating roller motor209is operated so as to change a transport length by forwarding/rewarding the compensating roller3as shown inFIG. 8. A varied length is detected by the rotary encoder211and counted by the counter210.

The compensating roller motor209is controlled by the CPU202in accordance with a position determined by the register mark detector206so as to cut a web member correctly.

As a cut-off-control device200, it may be employed another apparatus for controlling a cutting position of a printed web member in addition to the apparatus as shown inFIG. 1.

FIG. 2shows an operation flow chart of the control device100so as to switch on/off the cut-off-control device200by comparing a present revolution number and a memorized revolution number of a printing press.

At first, a start switch is switched on (step S1). In the case where an actual printing signal is switched on in the printing press (step S2), an actual revolution number of the printing press in the actual printing operation is read out (step S3).

The setting revolution number of the printing press in an actual printing operation is previously determined by the device122for setting a set revolution number and memorized in the memory120for memorizing/outputting a set revolution number.

A revolution number of the printing press in the case of switching on/off the cut-off-control device200is computed (step S4).

For example, it is computed a revolution number of the printing press when a tensile force of a web member is stable, that is, 95% of a revolution number of the printing press in the actual printing operation memorized in the memory120for memorizing the set revolution number.

The computed revolution number is memorized in the memory means109.

Successively, the present revolution number of the printing press is read out from the memory121for memorizing the present revolution number (step S5) and it is judged whether the present revolution number of the printing press is larger than a revolution number of the printing press in the case where the cut-off-control switch200is switched on/off (step S6).

The revolution number of the printing press is detected by the rotary encoder112of the printing press driving motor112through F/V111.

If the present revolution number of the printing press is larger the revolution number of the printing press in the case where the cut-off-control device200is switched on/off, the cut-off-control device200is begun to be controlled (step S7).

The present revolution number of the printing press is read out in the memory121for memorizing the present revolution number (step S8) and it is judged whether the present revolution number of the printing press is less than the revolution number of the printing press in the case where the cut-off-control device200is switched on/off (step S9).

If the present revolution number of the printing press is less than the revolution number of the printing press in the case where the cut-off-control device200is switched on/off, the cut-off-control device200is stopped to be controlled (step S10).

The operation is finished by switching off the start switch (step S11).

FIG. 3shows the second embodiment according to the present invention of a control device for controlling an apparatus for controlling a cutting position of a web member.

The embodiment employs an input device including an allowable value inputting device104a, a memory115for memorizing/outputting a reference tensile value, a memory116for memorizing/outputting an allowable value, and a memory117for memorizing a present tensile value of a web instead of the memories109,120, and121employed in the first embodiment. Further, the second embodiment employs a detector212for detecting a tensile force of a web member instead of the rotary encoder112of the printing press driving motor.

The memory115for memorizing a reference tensile value (reference tensile value memory) and the memory116for memorizing an allowable value (allowable value memory) are utilized for memorizing a tensile value of a web member in the case where the cut-off-control device200is switched on/off.

FIG. 4andFIG. 5show one example of an operation flow of the above control device100.

FIGS. 4 and 5are an operation flowchart so as to switch on/off the cut-off-control device200by comparing a tensile force of a web member, that is, a tensile value applied on the web member.

At first, a start switch is switched on (step T1). When a beginning signal for an actual printing operation of the printing press is turned on (step T2), a tensile value of the web member is detected (step T3). The detected tensile value of the web member is memorized in a memory115for memorizing a reference tensile value (step T4).

The present tensile value of the web member is detected by a tensile value detector212as means for measuring a tensile force of a web member and memorized in the memory117for memorizing the present tensile value of a web member1through A/D118and I/O110.

After passing a predetermined period (step) T5, a tensile value memorized in the reference tensile value memory is read out (step T6), an allowable value is read out from the allowable value memory116(step T7), and a present tensile value of a web member is read out (step T8). The allowable value is previously input from the allowable value input device104ain the input device104to the memory116for memorizing an allowable value.

Successively, it is judged whether a difference between the tensile value read out from the reference tensile value memory115and the present tensile value read out from the memory117for memorizing a present tensile value is within a range of an allowable value (step T9). If the difference is within the range of the allowable value, the cut-off-control device20is started to be controlled.

Unless the difference is within the range of the tensile allowable value, the present tensile value of the web member is input to the reference tensile value memory115(step T11). Then, a process from the step T5to the step T9is repeated.

After passing the predetermined time (step T12), the tensile value memorized in the reference tensile value memory115is read out (step T13), the tensile allowable value is read out from the tensile allowable value memory116(step T14), and the present tensile value of a web member is read out, from the memory117for memorizing a present tensile value (step T15).

It is judged whether a difference between the tensile value read out from the reference tensile value memory115and the present tensile value of the web member read out from the memory117for memorizing a present tensile value is larger than a tensile allowable value (step T16). If the difference is larger than the tensile allowable value, the cut-off-control device200is stopped to be controlled (step17).

On the other hand, unless the difference is larger than the tensile allowable value, the present tensile value is input to the reference tensile value memory115(step T19), a process from step T12to a step T16is repeated.

Then, the start switch is turned off (step T18), the control operation is stopped.

FIG. 9shows the third embodiment of a control device for controlling an apparatus for controlling a cutting position of a web member according to the present invention.

In the third embodiment, an input device in a control device100includes a reference tensile value inputting device104band an allowable value inputting device104a. A reference tensile value previously memorized from the reference tensile value input device104bin the input device104to the reference tensile value memory115and an allowable value previously memorized from the allowable value memory input device104bin the input device104to the allowable value memory116are utilized. The other structure of the third embodiment is as similar as the structure as shown inFIG. 3. Therefore, the other explanation is omitted.

FIG. 6shows an operation flow of the control device100of the third embodiment.

At first, a start switch is turned on (step U1). When a signal for starting an actual printing operation in a printing press is generated (step U2), a reference tensile value is read out from a reference tensile memory115(step U3), a tensile allowable value is read out from the tensile allowable memory116(step U4), and a present tensile value of a web member is read out from the memory117for memorizing a present tensile value (step U5).

It is judged whether a difference between the tensile value read out from the reference tensile value memory115and the present tensile value of the web member read out from the memory117for memorizing a present tensile value is within a range of the tensile allowable value (step U6). If the difference is within the range of the tensile allowable value, a cut-off-control device200is started to be controlled (step U7).

On the other hand, unless the difference is within the range of the tensile allowable value, a process from the step U5to the step U6is repeated.

Successively, a present tensile value of the web member is read out from the memory117for memorizing the present tensile value (step U8).

Further, it is judged whether a difference between the reference tensile value memory115and a present tensile value of the web member read out from the memory117for memorizing the present tensile value is greater (step U9). If the difference is larger the tensile allowable value, the cut-off-control device200is stopped to be controlled (step U10).

Then, the start switch is turned off (step U11), the control operation is stopped.

As described above with reference to the embodiments, in the present invention, an apparatus for controlling a cutting position of a cutting unit in a printing press is switched on/off in accordance with a present revolution number with respect to a revolution number in an actual printing operation or the stability of a tensile value of a web member. A compensating roller can be returned to a correct position in a short period of time so that cutting can be operated correctly and waste of printing material can be avoided.

Having thereby described the subject matter of the present invention, it should be apparent that many substitutions, modifications, and variations of the invention are possible in light of the above teachings. It is therefore to be understood that the invention as taught and described herein is only to be limited to the extent of the breadth and scope of the appended claims.