JPS6016593Y2 - Unwinding sheet tension control device - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a tension control device for an rewound sheet, and its purpose is to precisely control the tension of the rewound sheet and thereby improve the registration control accuracy of a rotogravure rotary press.

For example, conventional sheet feeding devices generally perform rough tension control by adjusting the rewinding braking force of the raw material sheet roll.

The tension of the traveling sheet is determined by the traction force of the pull-out nip roller or the take-up shaft and the corresponding braking force on the dancer roll side.

In general, raw material sheets often have some deflection in the width direction, and during winding, the deflected portions overlap at the same position, so other parts must be slightly lifted and the entire sheet should be wound softly.

Raw sheet rolls so wound tend to become oval under their own weight during storage.

When this is attached to the shaft of a rewinding device and the sheet is pulled out, periodic speed changes and tension changes occur in the running sheet.

Therefore, for example, in the sheet supply section of a recent gravure rotary press, the sheet in the above-mentioned state is passed through a set of nip rollers before being fed into the printing section to prevent the influence of the irregular shape of the raw material roll.

However, even the nip rollers cannot eliminate tension fluctuations in the running sheet, and the sheet is fed to the printing section with some tension fluctuation remaining.

If the sheet tension varies, its length (elongation) varies, so the spacing of each unit registered in the standard state must be corrected one after another, making the known automatic registration device busy.

Naturally, there will be some defective parts that cannot be completely corrected.

The effect is particularly large when the sheet is a plastic film.

Furthermore, when printing speeds are increased to increase printing productivity, the influence of the above-mentioned raw material rolls increases.

This invention uses a new method for controlling the tension of the unwound sheet, which does not rely on conventional winding (pulling) torque or unwinding braking torque.

It applies a load directly to the intermediate portion of the running sheet to generate the required tension.

Specifically, a load is applied to the traveling sheet by a floating roll such as a dancer roller, which is conventionally used to remove slack in the sheet, and the load is controlled to create the required tension in the sheet.

The seat travel drive mechanism is the same as before, and is simply a dancer.
It is sufficient to automatically control the roll so that it does not displace excessively.

This invention will be explained below with reference to the drawings.

FIG. 1 shows one of the best examples of a conventional gravure rotary press sheet supply section.

Raw material roll S. The sheet S is pulled out by a set of nip rollers 1, and its tension is measured by a detection device 2 along the way.

The measured value is fed back to the DC motor or brake 4 of the rewinding device via the control section 3 to adjust the sheet tension.

However, the aforementioned raw material roll S. Due to the irregular shape of the sheet S, the tension fluctuation of the sheet S is large.

The sheet S that has passed the nip roller 1 generates new tension due to the restraining force of the nip roller 1 and the pulling force of the printing section 5 and the winding section, but the wave of tension fluctuation that occurred in the previous stage only becomes smaller. .

In this case, the tension detection device 2', control section 3', and nip roller 1 drive motor 4' operate in the same way as in the previous stage, but this feedback control is only rough, and normally the nip roller drive section, which intervenes with a worm to prevent tangling, operates in the same manner as the previous stage. It is impossible to have a quick response that cancels out the waves of tension fluctuations.

Now, FIGS. 2 and 3 show explanatory diagrams of the second embodiment of this invention.

The main part is the sheet roll S.

Rewind device 11, sheet roll S.

The sheet S is pulled out and supplied from the holder, or between the two sets of nip rollers 12, 12a, the unwinding device 11, and the nip roller 12,
Alternatively, it may be a dancer roller mechanism 13.13a provided between the front and rear nip rollers 12.12a.

The dancer roller mechanism 13 includes well-known guide rollers 25, 25.
and a dancer roll 14, or a precise control mechanism for the load applied to the traveling seat S by the dancer roll 14,
In this example, an electromagnetic powder clutch 15 is provided.

In this case, the dancer roll 14 is supported at both ends by the tip of a swinging arm 26 which is a support mechanism, and the powder clutch 15 included in the drive mechanism attached to the swinging shaft 16 is as clearly seen in FIG. The input side is constantly rotated by the motor M, and the output side is biased to move the position of the swing shaft 16 of the dancer roll 14 while slipping.

The direction in which the swing shaft 16 is biased is, for example, a direction in which the dancer roll 14 is pressed against the sheet S if it is light, and a direction in which the rolling down of the sheet S due to the weight of the dancer roll 14 is weakened if it is heavy.

As is well known, the transmission force of the electromagnetic powder clutch during slipping can be precisely controlled electrically, so the load on the sheet S by the dancer roll 14 and the tension of the sheet S due to this can also be precisely controlled.

Arrow A to powder clutch 15 indicates manual, automatic tension setting and feedback input.

The drawing speed of the nip roller 12 and the rewinding speed of the rewinding device 11 are related as before.

The dancer roll support shaft of the rewinding device 11 may be braked or driven by a DC motor, but since the latter is shown in FIG. Insert into circuit 18 and sheet roll S again.

Also enter the rotation speed Nw.

Sheet roll S. The radius R at the start of rewinding is also calculated by the calculation circuit 18.
Since it is in a sheet roll S.

The rotation of the DC motor of the unwinding device 11 is increased as the diameter of the unwinding device 11 decreases.

A potentiometer 19 is attached to the swing shaft 16 of the dancer roll 14 to detect the displacement of the roll 14, and the displacement from the standard position is input to the arithmetic circuit 18 to reduce the displacement to a small range. It is controlled so that

However, the means for detecting and transmitting the displacement of the dancer roll 14 is left to the designer.

Figure 3 shows the 4th and 5th cases in which this idea was applied to a gravure rotary press.
It is a diagram explaining the principle of the embodiment shown in the figure.

In this case, the nip rollers 12, 12a1 and the dancer roller mechanisms 13, 13a are controlled in a double manner to control the raw material roll S.

The tension fluctuation due to the irregular shape of S is completely eliminated.

X, Y, and Z at the top of Fig. 3 are the primary, secondary, and
The tension region of each third order is shown.

The sheet tension in area X is the sheet roll S which is the source of tension fluctuation.
.

, the tension of the sheet S is still unavoidable, although it is less than before due to the nimble action of the primary dancer-roller mechanism 13.

When the sheet S enters the area Y, the front and rear nip rollers 1
A dancer that acts on the middle part of the seat regardless of 2 and 12a.
Due to the inertial tension generating mechanism of the roller mechanism 13a, the fluctuating tension is changed to a newly created uniform tension.

It then enters region Z and is wound up after passing through each printing unit with the required uniform tension.

Moreover, in this embodiment, it is only necessary to supply a sheet without stress fluctuation.

Conventional automatic registration devices have three methods: adjusting the length of the sheet path between each unit of the printing section or adjusting the rotation angle of the plate cylinder, but a new method is to adjust the tension (elastic stretch) of the supplied sheet. We have demonstrated that this goal can be achieved to some extent through control.

If there are no tension fluctuations in the sheets being fed, there is no way that each accurately manufactured unit will have varying advances or lags.

The overall advance and lag can be eliminated by adjusting the sheet tension of the feeding device of this invention.

In the case of unit manufacturing errors, the operating range of the respective automatic registration device is also significantly reduced.

Specifically, a control device that receives a pitch deviation (positional deviation of a multicolor pattern) detection signal C from a well-known register control sensor of the printing unit 5, in the case of FIG. Dancer-roller mechanism via 13.13
By adjusting the transmission torque of the powder clutch 15.15a, the load on the running sheet S of the dancer rolls 14, 14a is adjusted, and the tension of the supply sheet is adjusted.

Depending on how you think about it, in the past, the role of the register correction roller attached to each unit was performed by the dancer roll 14 of the sheet feeding device.
It can be said that 14a undertook the work.

Note that this feedback control may be applied only to the secondary dancer-roller mechanism 13a.

The role of controlling the tension of running sheets has expanded from the conventional convenience of unwinding and winding to color control of printing presses.

The control sensor 20 also includes potentiometers 19, 1 for detecting displacement of the front and rear dancer rolls 14, 14a.
9a, the DC motor 2 for correction of the winding device 11 and the primary nip roller 12 is activated via the control unit 21C*21a.
I am giving instructions to 2.

This motor 22 corrects the rotational speed of the primary nip roller 12 via a differential device 23.

The differential device 23 is fixedly rotated by a line drive section of the printing section 5.

Note that the secondary nip roller 12a is also driven by the line drive unit via a speed reducer 24.

The displacement of the dancer rolls 14, 14a is immediately caused by the unwinding device 1.
1. The sheet roll S is fed back to the differential device 23 in the direction of correcting its displacement.

, to adjust the rotation of the nip roller 12.

Note that the control unit 21c in FIG. 3 becomes the control unit 18 in FIG. 2 when the rewinding device 11 uses a DC motor, and when the rewinding device 11 uses a DC motor but uses braking control, it controls the pulling out of the primary nip roller 12 using a well-known technique. Match the speed.

4 and 5 show an embodiment of the one shown in FIG. 3, in which the unwinding device 11 is a sheet roll S.

It is a model that can prepare two.

The printing section 5 shown in FIG. 5 uses a method developed by the present inventor in which the guide roller is actively driven to match the circumferential speed of the plate cylinder and the impression cylinder. However, it does not matter if it is a non-droplet or conventional printing section.

As explained above with reference to a small number of embodiments, this invention is characterized by controlling the tension of the rewinding sheet by controlling the load of the dancer-roller mechanism, regardless of the traveling drive mechanism. Naturally, it changes in various ways.

The name of the dancer roller mechanism itself is the same as that of the conventional one for preventing loosening, but it is not intended to prevent loosening.
Any device may be used as long as it has floating rolls and guide rollers that generate general tension by applying a local load (thrust force) to the traveling sheet.

In addition, conventional equipment that biases the dancer roll with a pneumatic cylinder or the like to make the loosening movement easier is as follows:
If its control accuracy and responsiveness can be improved, it can be used for rotary presses.

Further, the dancer roll 14 of the above embodiment can transmit power along the swinging arm 26 and can be driven in synchronization with the seat.
The influence of the inertia of the roll 14 on the traveling sheet can be eliminated.

It is also free to add tension detectors or regular dancer rollers to the running path.

The manner in which this invention is applied to a rotogravure rotary press can vary in various ways.

This invention controls the tension of the rewinding sheet, completely independent of its drive mechanism and traveling speed.

The control mechanism uses a dancer roll that can be adjusted much more easily than a sheet roll unwinding device or nip roller drive mechanism, which improves the precision and responsiveness of tension control and makes automatic adaptive control of sheet tension much easier. did.

This invention also confirmed that by eliminating the influence of sheet tension fluctuations in the color control of rotogravure rotary presses, it was possible to correct pitch deviations by controlling the tension of the sheet supply section. It was shown that control accuracy and quick response work effectively.

That is, this invention has made a considerable contribution to the technical field of handling rewound sheets, particularly to the advancement of automatic adaptive control of sheet tension related to rotogravure rotary presses.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of a conventional sheet feeding mechanism in a rotogravure rotary press, Figs. 2 and 3 are explanatory diagrams of the principle of two embodiments of this invention, and Fig. 4 is an elevational view of a specific embodiment of Fig. 3. FIG. 5 is also a plan explanatory view, in which S is a seat and 13 is a dancer.
The roller mechanism, 14 is its dancer roll, and 15 is a load control mechanism (electromagnetic powder clutch).

Claims (1)

[Scope of utility model registration request] In a gravure rotary press, a sheet is drawn out and fed from a sheet roll, or two sets of nip rollers, a dancer roller mechanism provided between the sheet roll and the nip rollers or between the front and rear nip rollers, and a dancer roller of this dancer roller mechanism are used. A drive mechanism containing an electromagnetic powder clutch that urges the dancer roll to apply a required load to the running sheet, a biasing force precision control mechanism thereof, and the biasing force precision control mechanism in response to a pitch deviation signal from a printing section register control sensor. 1. A tension control device for a rewinding sheet, comprising: a control device that increases or decreases the running sheet tension in the direction of decreasing pitch deviation.