JPS6149220B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tension control device for controlling the tension of a material at an intermediate portion of a processing machine for processing long materials such as film and paper.

Conventionally, there are various known types of devices of this kind. For example, Tokuko Sho 53-27436
The type of control shown in this issue uses the following control method.

That is, the speed of the driven roller is controlled by an overspeed clutch, an underspeed clutch, and a speed control device to control the position of the dancer roller.

Furthermore, in order to stably control the position of the dancer roller, the dancer roller position signal and position differential signal are used as feedback signals for automatic control.

However, the conventional device has the following drawbacks and is practically impossible to implement in some areas.

For example, in rotogravure printing presses, it is well known that the diameter of the printing plate cylinder varies depending on the picture to be printed. Therefore, even if the number of rotations of the line shaft of the printing press remains the same, the running speed of the web changes by the amount that the diameter of the plate cylinder changes. This value is 1:2 on a normal printing machine.
This value has a wide range of magnitude, and has the disadvantage that it deviates from the speed control range of ±4 to ±10% of the conventional device described above and becomes uncontrollable.

In addition, in the case of a type that applies rotational torque to the dancer roller using an air cylinder, etc., the frictional force of the cylinder and the frictional force of the fulcrum act during the rotational operation of the dancer roller, and by the time the dancer roller starts moving, it is equivalent to the web. This has the drawback that tension fluctuations occur, and processing and printing failures occur when processing and printing materials are easily stretched, such as polyethylene film and vinyl film.

This invention was made to eliminate the drawbacks of the conventional devices as described above, and uses a combination of speed control loop and tension control loop to control the driven roller, achieving high precision that could not be achieved by controlling the position of the dancer roller alone. , provides a highly responsive tension control device.

FIG. 1 is a diagram showing an embodiment of the present invention in which the apparatus is used in a printing press.

FIG. 2 is a block diagram of a control device used in the present invention. In the figures, the same reference numerals indicate the same parts.

This will be explained below using figures. In FIG. 1, 1 is a web. This web 1 is engaged with an infeed roller 2, and is run through a dancer roller 3, a tension detection roller 4, a printing press 16, and an outfeed roller 12 in this order, and is printed. The rubber roller 6 and the rubber roller 13 are pressed against the infeed roller 2 and the outfeed roller 12 by an air cylinder or the like (not shown), respectively, so that the web 1 is fed out without slipping on the surfaces of the rollers.

5 is a tension detector, and 7 is a pivot point for rotating the dancer roller 3. An air cylinder 8 is mounted on an arm connecting the fulcrum 7 and the dancer roller 3, and is supplied with air from an air source (not shown) so as to be able to apply tension to the web 1. 18 is a rotational position detector of the dancer roller 3, which uses, for example, a differential transformer. 10 is a DC generator (hereinafter referred to as PLG), and the output signal 10
S serves as a reference for the running speed of the web 1 and generates a signal of positive polarity. 11 is a continuously variable transmission whose input shaft is connected to the line shaft 9 and whose output shaft is connected to the PLG 10 and the outfeed roller 12. this
The PLG 10 detects the traveling speed in the material processing section. 9M is a main electric motor that drives the entire printing press via the line shaft 9. 14 is a DC generator (hereinafter referred to as PG) that detects the rotational speed of the infeed roller 2, that is, the circumferential speed of the infeed roller 2.

The infeed roller 2 is configured to be driven by the line shaft 9 via a clutch brake unit 15. 15B is the brake side in the clutch/brake unit 15. 15C is clutch, brake unit 1
5 on the clutch side. Reference numeral 17 denotes a control device that comprehensively and automatically controls the device of the present invention. 5S is an output signal of the tension detector 5, which represents the tension of the web 1.

18S is the rotational position detector 1 of the dancer roller 3
When the dancer roller 3 is at the center of rotation according to the position detection signal 8, the signal voltage is zero, and when it is pulled by the web 1 and moves upward, it becomes a positive signal, and when it moves downward, it becomes a negative polarity signal. Become. 14S is an output signal of the PG 14, that is, a peripheral speed signal of the infeed roller 2.

Next, the control device 17 will be explained with reference to FIG.

In the figure, 5S is a tension detection signal, 18S is a dancer roller position detection signal, 10S is a running speed reference signal, 14S is a circumferential speed signal of the infeed roller 2,
A differentiator 171 differentiates the tension detection signal 5S and adds the resulting value to the adder 177. Reference numeral 172 denotes a servo calculator, which is designed to obtain an amplification rate proportional to the traveling speed reference signal 10S. The servo calculator 172 receives the dancer roller position detection signal 18S as an input signal and can obtain an output signal multiplied by the amplification factor described above. This output signal is also applied to adder 176. Infeed roller peripheral speed signal 14S
is added to adder 178. A comparator 173 includes a proportional and integral control circuit that determines the polarity of the output signal of the adder 178 and energizes the power amplifier 174 or 175. The power amplifier 174
When the input signal of the comparator 173 is positive, the clutch side 15 of the clutch/brake unit 15 is
energize C. Further, the power amplifier 175 is configured to energize the brake side 15B of the clutch/brake unit 15 when the input signal of the comparator 173 is of negative polarity. In addition, dancer roller 3
The position detection signal and the detection signal of the tension detector 5 are used because the detection signal of the tension detector 5 alone cannot cope with large tension fluctuations in the web.

The operation of the embodiment apparatus configured as above will be explained below.

When the main motor 9M starts rotating, the outfeed roller 12 and PLG 10 are driven via the continuously variable transmission 11, and the printing press 16 is also driven, so the web 1 starts running. PLG10
By the traveling speed reference signal 10S transmitted from
First, the input terminal of the comparator 173 becomes positive polarity,
Via the power amplifier 174, the clutch side 15C of the clutch/brake unit 15 is energized to drive the infeed roller 2 and PG 14. PG14
The peripheral speed signal 14S of the in-feed roller 2 transmitted from the in-feed roller 2 is added to the adder 178 as a negative polarity signal when the in-feed roller 2 starts rotating. Therefore, when the circumferential speed of the infeed roller 2 becomes higher than the running speed reference signal 10S, the input signal of the comparator 173 becomes negative, and the clutch,
The brake side 15B of the brake unit 15 is energized to act in a direction to reduce the circumferential speed of the infeed roller 2. In this way, by controlling the clutch side 15C and brake side 15B of the clutch and brake unit 15 with the control device 17,
The peripheral speed of the infeed roller 2 can be synchronized with the peripheral speed of the outfeed roller 12. The dancer roller 3 is centered around the fulcrum 7,
It rotates in a circular arc in the direction in which it is pulled by the web 1 or in the opposite direction. Dancer roller 3 has
A stopper is provided to prevent the arm connecting the axis of the dancer roller and the fulcrum from moving more than necessary in the vertical direction about the horizontal point, but this is well known and is not particularly shown.

Differential transformer 18 for detecting the position of the dancer roller
is the center of rotation of the dancer roller as described above, and the dancer roller position detection output signal 18S
is approximately 0, and when pulled upward by the web 1, a positive polarity signal is generated, and conversely, when rotated downward, a negative polarity signal is generated. This dancer roller position detection signal 18S is transmitted to the servo calculator 172 as an input signal. As mentioned above, the servo calculator 172 has an amplification rate proportional to the traveling speed reference signal 10S. Therefore, adder 176
A value obtained by multiplying the traveling speed reference signal 10S and the dancer roller position detection signal 18S by the amplification factor of the servo calculator 172 is applied as an output signal of the servo calculator 172, that is, a correction signal for the dancer roller position. The ratio of the running speed reference signal 10S to the rotation of the dancer roller 3 is ±
A value of around 5% has given good results experimentally.

As can be understood from the above explanation, the dancer roller position detection signal, 18S, is the running speed reference signal 1.
Infeed roller peripheral speed signal 14 for 0S
The error of S is integrated and fed back, so that both can operate in constant synchronization.

Therefore, the web 1 includes the dancer roller 3.
The value obtained by adding the own weight of the air cylinder 8 and the tension applied by the air cylinder 8 is applied as the tension.

Normally, when this type of control is performed, the peripheral speed of the infeed roller changes slightly due to disturbances on the machine side and disturbances on the unwinding side (not shown), and the dancer roller 3 moves slightly up and down, constantly making corrections. is repeated. This dancer roller 3
The fine vertical movement causes tension fluctuations in the web 1, which seriously affects printing accuracy. The causes of this tension variation are as follows. The first is the tension variation generated to accelerate the combined mass of the dancer roller 3 and the air cylinder 8 in the upward and downward directions.

The second is the friction torque of the fulcrum 7, and the third is the sliding friction force of the air cylinder.

The fourth reason is that the piston of the air cylinder 8 moves as the dancer roller 3 moves up and down, and exhaust pressure is generated in the air pipe (not shown).

If we consider the causes of tension fluctuations in Parts 1 to 4 above, the following can be said. That is, if the vertical movement speed of the dancer roller 3 is made as slow as possible, the tension fluctuation generated in the web 1 becomes extremely small.

The present invention has been made in view of the above points, and uses the differential signal of the tension detector 5 to suppress the vertical movement speed of the dancer roller 3.

Another method to achieve the same effect is to use a weight to apply tension to the web 1 without using the air cylinder 8, which is the biggest cause of tension fluctuations. However, the method using this weight is
The total mass of the dancer roller 3 increases, and the value of the first cause of tension fluctuation described above increases in a negative direction. Furthermore, when changing the tension value applied to the web 1, the weight must be changed, which has the disadvantage of poor workability. When the air cylinder 8 is used, the tension value applied to the web 1 can be freely adjusted over a wide range simply by adjusting the air pressure using a control valve (not shown). Another advantage is that remote control is possible. For this reason, air cylinders are often used. The tension detection value 5S detected by the tension detector 5 is determined by the differentiator 171.
, and is converted into a control signal according to the tension change value and change speed, and is applied to the adder 177.
Therefore, for example, when the tension of the web 1 increases due to some disturbance, the dancer roller 3 is pulled upward, the infeed roller 2 is accelerated by the dancer roller position detection signal 18S, and the dancer roller 3 moves downward again to a predetermined position. It returns to its stable position. During this control process, the tension detection value 5S of the tension detector 5 is detected at the same time as the tension of the web 1 increases, that is, before the time-delayed signal indicating that the dancer roller 3 is pulled upward is generated. A correction signal can be given to the adder 177, and the circumferential speed of the infeed roller 2 can be corrected very quickly. In addition, it is particularly effective for webs such as polyethylene film, which are extremely stretchable and cannot be expected to produce a good print finish unless operated under very small tension. Webs that are operated under minute tension are generally susceptible to minute tension fluctuations that are not enough to cause the dancer roller 3 to move up and down, due to the frictional force caused by mechanical parts such as the air cylinder 8 that are engaged with the dancer roller 3. There are many examples where printing misalignment occurs, and many of these misalignments result in printing failures.

However, in the control system according to the present invention, by feedback correction of the tension detection signal 5S, the circumferential speed of the in-feed roller 2 can be sufficiently controlled even when the tension fluctuates to such an extent that the dancer roller 3 does not move due to frictional force. It is possible to obtain excellent control performance in that an optimum elongation rate, that is, tension can be applied to the web 1.

Another advantage of the apparatus of the present invention is that it employs a system in which the infeed roller 2 is driven by the clutch and brake unit 15, so that a very wide speed control range can be easily obtained. This makes it possible to accommodate changes in the diameter of the plate cylinder of the printing press 16.

In order to obtain the same effect with a conventional device, for example, in Japanese Patent Publication No. 53-27436, a continuously variable transmission that can at least accommodate changes in plate cylinder diameter is installed between the line shaft and the input shafts of the overspeed clutch and underspeed clutch. It is necessary to readjust the speed change rate of the continuously variable transmission every time the plate cylinder is changed, which requires wasted space and cost.

In order to obtain the same effect with other conventional devices, it is necessary to use a variable speed motor, such as a DC motor, resulting in a drive device that is more expensive than the device of the present invention.

In this embodiment, an example is described in which a DC generator is used for the PLG 10 and PG 14, but an AC generator may also be used, or a pulse generator and a frequency-voltage converter may be used. The position detection device 18 of the dancer roller 3 is not a differential transformer, but a variable resistor or other device that can detect the position and angle and has the same function and effect can be used.

Even better results can be obtained if the power amplifiers 174 and 175 adopt an overvoltage application type circuit, which is often used to improve the responsiveness of clutches and brake units, or a constant current drive type circuit. This is well known.

Further, the clutch and brake unit 15 may be of any type as long as they can continuously control the coupling torque and braking torque over a wide range.
In particular, using powder clutches and brakes is
It has advantages in terms of availability, maintenance, and controllability.

As explained above, the present invention uses the infeed roller circumferential speed signal 14S and the dancer roller position detection signal 18S as feedback signals for matching the infeed roller drive mechanism by the clutch brake unit 15 with the traveling speed reference signal 10S. Furthermore, a tension detector 5 is provided so that fluctuations in the tension of the web 1 can be detected before the dancer roller 3 rotates, and a differential signal from the tension detector 5 is configured to be fed back, so that the tension can be detected with very high precision. It has the advantageous effect that it is possible to control from a large tension to a minute tension range, and furthermore, it is possible to construct an inexpensive tension control device that does not require readjustment when changing printing plate cylinders and does not take up much space.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of the device of the present invention;
FIG. 2 is a block diagram of the control device of the apparatus of the present invention. 1...Web, 2...Infeed roller, 3
...Dancer roller, 4...Tension detection roller,
5...Tension detector, 9M...Electric motor, 10...First speed detector, 15...Clutch, brake unit, 14...Second speed detector, 17...Control device, 18...Dancer roller position detector,
171... Differentiator. In the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A prime mover, a first speed detector that detects the traveling speed in the processing section of the material whose traveling speed is determined by the prime mover, which engages with the material, is freely supported in rotation, and applies tension to the material. A movable dancer roller, a position detector for detecting the moving position of the dancer roller, a clutch capable of applying driving and braking torque to the infeed roller from the prime mover and controlling the circumferential speed of the infeed roller, a brake unit, and the brake unit. a second speed detector that detects the circumferential speed in the material supply section of the in-feed roller; a tension detector that detects the tension in the material processing section; a differentiator that differentiates the detection signal of this tension detector; a comparator that compares a signal corrected by applying the detection signal of the position detector and the output signal of the differentiator to the detection signal of the first speed detector and the detection signal of the second speed detector. and a tension control device that controls the clutch and brake unit based on the output of the comparator so that the circumferential speed of the infeed roller matches the traveling speed in the processing section.