JPH06611B2 - Control method in dancer roll type tension control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention unwinds (winds up) a web material such as roll paper.
It relates to a method for controlling the tension acting on a web material in a driven feed. More specifically, the present invention relates to a tension control method suitable for a feeding mode in which abrupt tension changes repeatedly occur in a web in a relatively short time cycle.

(B) Prior Art As a tension control device for web feeding, a tension control device using a dancer roll is known. This tension control device forms a corrugated traveling path between a pair of parallel guide rolls arranged along the web traveling path by diverting the web from the plane connecting these two rolls to one side. A dancer roll that is elastically supported at the position is displaceably arranged to absorb a sudden change in tension due to the displacement of the dancer roll that follows the web tension, and an unwind roll that returns the dancer roll to the initial position. Is controlled to control the web tension to a predetermined value.

Such a dancer roll type tension control device has an advantage that it is possible to absorb a sudden and large tension fluctuation by increasing the operation displacement width of the dancer roll (making the operation stroke longer). Therefore, when the dancer roll is used, the dancer roll is generally connected and supported by the working rod of the air cylinder in order to increase the working displacement range. For example, the web is arranged so as to form the corrugated running path by pressing the web in one direction by the pressing force of the air cylinder, and the pressing force of the air cylinder, the pressing force by the web tension, and the displacement It is configured to balance the acting force in the opposite direction such as the changing spring. More specifically, if the tension increases while the web is running (feeding) under a tension that is set in advance, the acting force of this tension displaces the dancer roll against the pressing force of the air cylinder. That is, the web supply amount is increased accordingly, and the increase in tension is absorbed. On the contrary, when the tension is decreased, the pressing force of the air cylinder becomes relatively large with respect to the acting force based on the tension, and the dancer roll is displaced in the direction of increasing the pressing displacement amount of the web and the feeding amount of the web. To act to maintain web tension and prevent tension loss. Tension control is performed and the dancer roll is returned to its initial position by absorbing the tension fluctuations by following the dancer roll's follow-up action to the web tension and controlling the braking of the rewind roll etc. The working width of is always guaranteed.

(C) Problems of the Prior Art In the conventional tension control device of this type, a constant air pressure is always applied to the pressing air cylinder of the dancer roll. If a constant air pressure is applied, the dancer roll will follow the movement so that it will always have the set tension value, and will work to obtain an equilibrium state.Therefore, the dancer roll following movement itself will work to restore the tension to the specified value. Have the advantage of Therefore, for example, when the tension fluctuation progresses very slowly, the tension can be controlled to be constant only by the follower displacement of the dancer roll. In this case, the braking control of the rewind roll or the like is performed by the dancer roll. It can also be said to guarantee the working width of the roll (although, in essence, the braking control of the rewind roll or the like fundamentally controls the web tension).

However, when the web tension changes abruptly and greatly, the follower displacement of the dancer roll increases correspondingly, and the time until the equilibrium state is obtained (assuming that the stroke of the dancer roll is sufficiently long) become longer. During this displacement, the web tension deviates from the predetermined tension level in any case, although the web tension may be larger or smaller than the predetermined tension depending on the displacement direction of the dancer roll.

Therefore, even if the braking of the rewinding roll or the like is controlled, the actual tension is kept at a predetermined value until the time required for the dancer roll to balance with the web tension and to reach an equilibrium state when this braking is not performed. Cannot be recovered. For this reason, when the web tension changes abruptly and largely, the displacement of the dancer roll is large, so that it takes time to recover, and the response of the tension control deteriorates.

(D) Object of the present invention The present invention improves the above-mentioned dancer roll type tension control device to obtain a better responsiveness to the feeding of a web in which rapid and large fluctuations in tension repeatedly occur, and the tension is improved. The purpose is to provide a controllable method.

(E) Outline of the invention Therefore, the method of the present invention is a dancer that supports a displaceable dancer roll arranged so as to form a corrugated traveling path on a traveling web by a cylinder device and follows a fluctuation in tension of the web. A displacement amount of movement of the roll is detected by a sensor, and a fluid pressure that changes in correlation with the displacement amount is applied to the cylinder device so as to control the movement of the dancer roll, and the displaced dancer is also applied. The braking of the web rewinding roll is controlled based on the displacement amount of the dancer roll so that the roll is returned to the initial setting position.

(F) Action In such a method according to the present invention, when the web is arranged so as to press the web to one side through the dancer roll by the pressing force of the air cylinder to form the corrugated running path as described above, the tension Regarding the displacement direction of the dancer roll that responds to the increase, the air pressure applied to the air cylinder is increased as the amount of displacement increases so as to suppress this displacement, and conversely the displacement direction of the dancer roll that responds to the decrease in tension is the same. In order to suppress this displacement, the air pressure applied to the air cylinder is lowered as the displacement amount increases.

Since the air pressure is changed according to the displacement of the dancer roll, there is no problem even if there is no force such as a spring that changes according to the displacement of the prior art.

When the tension suddenly increases due to disturbance such as web splicing, the dancer roll rises and the web is supplied more to reduce the tension.However, because the dancer roll is rising, the tension is higher than that before the disturbance entered. Equilibrate. When the tension suddenly decreases, the tension increases as the dancer roll descends and the web supply decreases.
Since the dancer roll is descending, it will equilibrate with a tension smaller than that before the disturbance entered. That is, the offset in the feedback control of the proportional operation remains. The braking of the rewinding roll is controlled so that the offset of the dancer roll is eliminated and a predetermined tension is obtained.

By imparting to the air cylinder an air pressure that changes in correlation with the amount of displacement of the dancer roll in this manner, the follower movement of the dancer roll in response to tension fluctuations is suppressed, and a balanced state is quickly obtained. It will be. By the way, in this equilibrium state, the actual web tension is slightly different from the predetermined tension. because,
Pressing force (air pressure) of the air cylinder in this equilibrium state
Is different from the pressing force (air pressure) in the initial equilibrium state. However, if the dancer roll is returned to the initial position by controlling the braking of the rewind roll at the same time, the pressing force (air pressure) of the air cylinder is returned to the initial pressing force (air pressure). The tension is restored to a predetermined value. In this way, the time from the time when the tension changes to the time when it is restored to the predetermined value is significantly shortened by the rapid equilibration of the dancer roll, and compared with the case where the constant air pressure is applied as described above. Responsiveness is remarkably improved. because,
This is because the time required to completely recover the tension essentially depends on the time required for the dancer roll to equilibrate.

(G) Example FIG. 1 shows a schematic configuration of a dancer roll type tension control device adopting the method of the present invention. In this device, a dancer roll 3 arranged in combination with a pair of guide rolls 1 so as to form a corrugated running path on a web 2 is connected to and supported by an operating rod 5 of an air cylinder 4. The piston 6 connected to the operation rod 5 is shown here as being initially set at the center position of the operation stroke of the air cylinder, and the displacement width in the upward direction in the drawing due to the increase in the tension of the web 2 is shown. , And the displacement width in the lower direction in the drawing due to the decrease in tension is both set to / 2.

Air pressure is applied to the air cylinder 4 so as to press the dancer roll 3 downward in the drawing. Here, in the drawing, the structure is shown in which the air pressure is applied only to the upper cylinder chamber 4a defined by the piston 6. This air pressure is supplied from an appropriate compressed air supply source 10 through an air pressure line L1 via a pressure regulator 11.

The pressure regulator 11 is for controlling the air pressure supplied to the air cylinder 4, and here, as will be described later, an electric output signal of the pressure control unit 30 is input through the control line L3, and this signal is input. The electro-pneumatic converter is configured to control the supply air pressure based on the above.

The air cylinder 4 is fitted with an appropriate sensor 12 for detecting the displacement amount of the dancer roll 3, that is, the displacement amount of the piston 6 from the initial setting position. The sensor 12 is only shown here schematically, but it goes without saying that known means can be used, for example in combination with the actuation rod 5 to detect its extension / contraction distance and generate an electrical output signal. is there. This detection signal (herein, an electric signal) is transmitted to the tension control unit 2 via the electric transmission line L2.
It is designed to be input to 0. Further, this detection signal is input to the pressure control unit 30 through the electric control line L6 branched from the line L2.

The tension controller 20 is for recovering the actual tension to the target value for tension control. For this reason, here, a pressure regulator 42 (a device similar to the pressure regulator 11 is connected to a line L4 that supplies an operating pressure (made to be an air pressure) to an air brake 41 that is assembled to the rewinding roll 40 of the web 2. ) Is provided and an electric control signal in response to the displacement amount of the dancer roll 3 is given to the pressure regulator 42 through the line L5, whereby the dancer roll 3 is set to the initial setting position (corresponding to the initial setting position of the piston 6). ) Has been designed to return to. The operating pressure of the air brake 41 is connected so as to be supplied from the air pressure supply source 10.

In the tension control method according to the present invention, since the air pressure supplied to the air cylinder 4 changes according to the position of the piston 6, the tension control unit 20 determines the initial position at which the piston 6 should be returned. By appropriately setting and maintaining the equilibrium state in this, the target tension value of the web can be arbitrarily set.

The pressure control unit 30 is the air cylinder 4 which is a feature of the present invention.
It is for controlling the operation of the pressure regulator 11 described above in order to control the air pressure supplied to the sensor 12. For example, as shown in FIG. 2, the detection output of the sensor 12 relating to the displacement amount (stroke position) of the piston 6 Is input, and a control signal is supplied to the pressure regulator 11 through the line L3 so as to supply the air cylinder 4 with an air pressure that changes in proportion to the displacement amount.

Here, the change in the air pressure shown in FIG. 2 is caused by the displacement of the air cylinder 4 when the dancer roll 3 is pushed in the direction of the air cylinder 4 because the tension of the web 2 increases.
When the dancer roll 3 is extended in the direction away from the air cylinder 4 by increasing the tension of the web 2 on the contrary so that the air pressure supplied to the
The air pressure is changed so that the air pressure supplied to the air cylinder 4 is reduced.

Further, in FIG. 2, three displacement amount-air pressure correlation lines a, b,
Although c is shown, the pressure control unit 30 is adjustable so that the air pressure can be controlled based on these arbitrary correlations.

In the apparatus configured as described above, as will be apparent from the above, the tension value during web running is appropriately set by the tension controller 20. Further, if the tension changes in the running of the web, the tension change first causes the dancer roll 3 to be displaced so as to follow the movement, and acts to absorb the change. At the same time, on the other hand, the pressure control unit 30 controls to supply the air cylinder 4 with the air pressure that changes in response to this displacement. In this control, the air pressure increases or decreases in the direction of suppressing the displacement of the dancer roll 3 in the method of the present invention, so that the follower of the dancer roll 3 tends to be quickly stopped and balanced. On the other hand, the tension controller 20 controls the operation of the air brake 41 so as to return the dancer roll 3 to the initial setting position,
This restores the tension to the set tension. By thus returning the dancer roll to the initial position in association with the rapid equilibration of the dancer roll 3, as described above, the response of the tension control is remarkably enhanced.

FIG. 3 shows the temporal relationship between the change in the web feed speed and the displacement of the dancer roll 3 in such an operation. Here, a case is shown in which abrupt web feed and abrupt web stop are repeated relatively frequently, but under the operating relationship shown in the figure, the tension is controlled with an extremely good response to a predetermined value. It was. Although the air brake 41 is controlled by the pressure regulator 42 in the above embodiment, the tension controller 20
An electromagnetic signal may be used to control the electromagnetic brake.
Also, instead of the air cylinder 4, a hydraulic cylinder,
The hydraulic pressure may be controlled by the pressure regulator 11.

(H) Effect In the present invention, the changing air pressure is applied to the air cylinder so as to suppress the displacement of the dancer roll that follows the tension fluctuation, so that the response of the tension control can be remarkably improved. In addition, by appropriately adjusting the degree of change in the air pressure, it is possible to adjust the responsiveness suitable for the web feed mode. The construction for this is simple and it is easy to retrofit existing equipment for the adoption of the method of the invention.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of a dancer roll type tension control device adopting the method of the present invention. FIG. 2 is a drawing showing a correlation between air pressure applied to an air cylinder for driving a dancer roll and a displacement amount, which is a feature of the present invention. FIG. 3 is a drawing showing the time relationship between the web feed speed and the dancer roll displacement. 1 ... Guide roll 2 ... Web 3 ... Dancer roll 4 ... Air cylinder 5 ... Rod 6 ... Piston 10 ... Compressed air supply source 11 ... Pressure regulator 12 ... Sensor 20 ... Tension controller 30 ... Pressure control unit 40 ... Rewinding roll 41 ... Air brake 42 ... Pressure regulator

Claims (1)

[Claims] 1. A displacement device, which is arranged so as to form a corrugated running path on a running web, is supported by a cylinder device, and a displacement amount of movement of the dancer roll that follows a change in tension of the web is detected by a sensor. Detecting and applying a fluid pressure that changes in correlation with this displacement amount to the cylinder device so as to suppress the movement of the dancer roll, and to return the displaced dancer roll to the initial setting position. A method of controlling a tension control device of a dancer roll type, characterized in that braking of a web rewinding roll is controlled based on a displacement amount of the dancer roll.