JPH04226250A - Method and device to generated approximately fixed web tension - Google Patents

Abstract

PURPOSE: To develop approximately constant web tension in a rotary press by decreasing or increasing the tension in a web traveling from a tensioning device, and compensating the obstruction force by the correlation of the friction factor with the web tension. CONSTITUTION: A web 27 is wound around a tension roller 4 at the specified adjustable winding angle α, and guided. The tension roller 4 is driven at the constant peripheral speed lower than the peripheral speed of a body of a succeeding printing device, and when the tension in a web 27 traveling into the tensioning device 1 is increased (or decreased), the sliding friction factor μbetween the tension roller 4 and the web 27 is decreased (or increased). The tension in the web 27 traveling from the tensioning device 1 to a printing device 3 is decreased (or increased) to compensate the obstruction force to generate the fluctuation in the web tension by the correlation of the sliding friction factor with the web tension.

Description

[Detailed description of the invention]

0001

FIELD OF THE INVENTION This invention relates to a method and apparatus for generating substantially constant web tension in rotary printing presses.

0002

BACKGROUND OF THE INVENTION It is known to provide tensioning devices in rotary printing presses, which tension devices are used to control the tension and movements of the web that may occur, for example, when unwinding the web from a roll of web. between the web reel changer and the subsequent printing device to avoid interference with the web roll exchanger.

Federal Republic of Germany Patent No. 23 05
No. 249 describes a tensioning device with a drivable tensioning roller and a dancer roller, the roller having a device for sensing variations in web tension. The tension roller is mainly driven by the main drive of the printing press and has a transmission device that changes the driving speed of this tension roller, and the control part of this transmission device is connected to the dancer roller via a regulating circuit. It is designed to be driven by an electric motor.

[0004] The tensioning device described in the above-mentioned German patent specification maintains the web speed constant by a principle based on the speed change of the tensioning roller. Such measures require a large number of additional structural parts, such as electric motors, differential transmissions, regulating devices, etc. Therefore, the structure of this tensioning device becomes complicated and the cost increases significantly.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and a device for generating substantially constant web tension in a rotary printing press.

[0006]

SUMMARY OF THE INVENTION According to the invention, the above object is achieved by means of the features of claims 1 and 2.

[0007]

According to the method and apparatus of the present invention, it is possible to adjust the tension of the web. Furthermore, among other things, complex adjustment devices and associated adjustment devices are not required. Furthermore, it is simple in construction, cost-effective and trouble-free.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A tensioning device 1 of a rotary printing press is arranged between a web reel changer 2 and a printing device 3 of the rotary printing press. The tension device 1 is connected to the side frame 8 via bushes 6 and 7.
, 9 has a tension roller 4 rotatably supported. The tension roller 4 is driven at reduced speed from the main drive of the printing press by a drive gear 11 which is supported on the journal 10 of the tension roller 4 on the outside of the side frame 9. By this measure, the circumferential speed of the tension roller 4 is lower (approximately 0.03%) than the circumferential speed of the cylinder of the following printing device 3.

[0009] The tension roller 4 when viewed in the conveying direction of the web 27
Behind the deflection roller 12 is arranged, which roller is rotatably mounted on an axle 13. The shaft 13 is adjustable in the side frames 8, 9.

[0010] The tension roller 4 when viewed in the conveying direction of the web 27
A web guide roller 14 is arranged in front of the web guide roller 14 . This roller is rotatably mounted on a shaft 16. axis 1
6 is supported on two pivotable levers 17, 18, which in turn are supported by pivotable gears 19, 18, respectively.
It is immovably connected to 21. Rotatable gears 19, 21
are pivotably supported on bushes 6, 7 inside side frames 8, 9, respectively. gear 19,
21 are each meshed with one of the two gears 22 and 23, and these gears are respectively meshed with the side frame 8.
, 9 is fixed to the shaft 13. The shaft 13 protrudes from the side frames 8 and 9 on both sides, and supports a handle 24 on the side of the side frame 8 which has a self-locking function for rotating the shaft 13 by hand. Of course, it is also possible in this case to provide an adjustment motor for remote control. On the opposite side frame 9 side, an adjustment indicator 26 in the form of a potentiometer is provided. Of course, it is also possible in this case to provide other forms of adjustment indicator, for example a graduated hand.

The web 27 enters the tensioning device 1 from the web reel exchanger 2 and is first guided around the web guide roller 14 in a clockwise direction and then fed to the tensioning roller 4 . The web 27 is wound counterclockwise around the tension roller 4 over a winding angle α (approximately 90°<α<270°) and then reaches the deflection roller 12. Before the web is fed to the printing device 3, it is wound around this deflection roller 12 again in a clockwise direction. The web guide roller 14 can be pivoted about the tension roller 4 with a center distance a by means of adjusting devices (24, 13, 19 to 23, 17, 18, 16). The wrapping angle α is adjusted by pivoting the web guide roller 14 about the tension roller 4.

The function of the tensioning device 1 according to the invention is as follows.

The tension roller 4 is driven at a lower circumferential speed relative to the web 27. The resulting web 2
Slip between 7 and tension roller 14 is accompanied by friction, resulting in web tension. There is a correlation between the sliding friction factor μ and the web tension. This relationship is as follows.

When the winding angle α is constant, the sliding friction factor μ decreases as the web tension increases, and increases as the web tension decreases. A reduction in the friction factor μ at the same time reduces the braking force exerted on the web 27 by frictional slip from the tension roller 4, so that the system described above automatically operates within a set working range (approximately ± daN disturbance force). adjusted accordingly. As the web tension decreases,
The sliding friction factor μ now increases inversely.

By changing the winding angle α, the working range can be adjusted to a desired working range.

[Brief explanation of the drawing]

FIG. 1 shows a schematic side view of a tensioning device roller;

FIG. 2 is a plan view of the tensioning device roller of FIG. 1;

[Explanation of symbols]

1 Tension device 2. Web roll exchanger 3 Printing device 4 Tension roller 6 Bush 7 Bush 8 Side frame 9 Side frame 10 Journal 11 Drive gear 12 Direction changing roller 13 Axis 14 Web guide roller 16 axis 17 Lever 18 Lever 19 Gear 21 Gear 22 Gear 23 Gear 24 Handle 26 Adjustment indicator 27 Web a Distance α Winding angle

Claims (6)

[Claims] Claim 1: In a method for generating a substantially constant web tension using a tensioning device (1), a web (27) is wound around a tension roller (4) and guided at a winding angle α, and the tension roller (4) is , driven at a constant circumferential speed lower than the circumferential speed of the cylinder of the following printing device (3), the tensioning roller ( 1) and the web (27), thereby reducing or increasing the web tension of the web (27) running from the tensioning device (1), and the friction factor (μ) A method for generating a substantially constant web tension, characterized in that the interfering force is compensated for by a correlation between and the web tension. 2. A device for generating an approximately constant web tension in a rotary printing press with a drivable tension roller (4), on which the web (27) is partially wound; Device for generating a substantially constant web tension, characterized in that means (14) are provided for varying the wrapping angle (α) of (27). 3. Device for generating an approximately constant web tension according to claim 1, characterized in that said means are constructed as pivotable web guiding rollers (14). 4. Apparatus according to claim 3, characterized in that the web guiding roller (14) is arranged pivotably at a distance (a) about the tensioning roller (4). A device that generates [Claim 5] The web guide roller (14) is connected to the shaft (16).
) and is rotatably supported on three levers (
17, 18) and two gear pairs (19, 22; 21, 2
5. Device for generating an approximately constant web tension according to claim 4, characterized in that the device is connected to the adjusting device (13, 24) via the adjusting device (13, 24). [Claim 6] The tension roller (1) is a deceleration means (11).
6. Apparatus for generating substantially constant web tension according to claim 5, characterized in that it is connected to the main drive of a rotary printing press via an apparatus.